This question involves decoding relationships based on a given set of symbols. We need to analyze each option by breaking down the coded string and determining the relationships between the individuals mentioned.

Understanding the Blood Relation Codes

Let's first understand what each symbol represents:

• P + Q means 'Q is the son of P'. This tells us P is a parent of Q, and Q is male.
• P @ Q means 'Q is the daughter of P'. This tells us P is a parent of Q, and Q is female.
• P $ Q means 'Q is the brother of P'. This tells us P and Q are siblings, and Q is male. P's gender is not specified.
• P % Q means 'P is the father of Q'. This tells us P is a parent of Q, and P is male.
• P # Q means 'P is the mother of Q'. This tells us P is a parent of Q, and P is female.

We can summarize these rules:

Analyzing Each Option to Find the True Blood Relation

We will now examine each option provided and trace the blood relations.

Option 1: C @ D $ F % G means G is the grandson of C.

• C @ D: D is the daughter of C. (C is parent of D, D is female)
• D $ F: F is the brother of D. (D and F are siblings, F is male). Since D is daughter of C, F is the son of C.
• F % G: F is the father of G. (F is parent of G, F is male). G is a child of F.

Based on this, C is the parent of F (since F is the brother of C's daughter). F is the father of G. So, C is the grandparent of G. For G to be the grandson of C, G must be male and the child of C's son. F is C's son, and G is F's child. We know F is male. However, the code F % G only tells us F is the father of G; it does not specify G's gender. G could be a grandson (male) or a granddaughter (female). Therefore, we cannot definitively say G is the grandson of C. This statement is not necessarily true.

Option 2: A + B $ C % D means A is the maternal grandfather of D.

• A + B: B is the son of A. (A is parent of B, B is male)
• B $ C: C is the brother of B. (B and C are siblings, C is male). Since B is son of A, C is the son of A.
• C % D: C is the father of D. (C is parent of D, C is male). D is a child of C.

Based on this, A is the parent of C (since C is the brother of A's son). C is the father of D. So, A is the grandfather of D. For A to be the *maternal* grandfather, A must be the mother of C. However, from A + B, we only know A is a parent of B and B is male; this does not specify A's gender. A could be male (paternal grandfather) or female (maternal grandmother). Therefore, we cannot definitively say A is the maternal grandfather of D. This statement is not necessarily true.

Option 3: K + L $ M @ N means N is the granddaughter of K.

• K + L: L is the son of K. (K is parent of L, L is male)
• L $ M: M is the brother of L. (L and M are siblings, M is male). Since L is son of K, M is the son of K.
• M @ N: N is the daughter of M. (M is parent of N, N is female). N is a child of M.

Based on this, K is the parent of M (since M is the brother of K's son). M is the father of N (as M @ N means N is daughter of M, so M is a parent). So, K is the grandparent of N. Specifically, M is the son of K, and N is the daughter of M. Therefore, N is the daughter of K's son. A daughter of a son is a granddaughter. N is female, which confirms she is a granddaughter. This statement, "N is the granddaughter of K," is true based on the decoded blood relations.

Option 4: G % H # K $ L means L is the son-in-law of G.

• G % H: G is the father of H. (G is parent of H, G is male)
• H # K: H is the mother of K. (H is parent of K, H is female)

From G % H and H # K, we know G is the father of H, and H is the mother of K. This makes G the maternal grandfather of K.

• K $ L: L is the brother of K. (K and L are siblings, L is male). Since H is the mother of K, H is also the mother of L.

Based on this, G is the father of H, and H is the mother of K and L. G is the maternal grandfather of both K and L. L is the brother of K, and L is male. For L to be the son-in-law of G, L would need to be married to G's daughter. G's only direct child mentioned is H, who is female. For L to be G's son-in-law, L would have to be married to H. However, L is the son of H. A son cannot be married to his mother. Therefore, L is not the son-in-law of G. L is G's grandson. This statement is false.

Conclusion on Blood Relations

After analyzing each option and decoding the blood relation strings, we find that only the third statement, "N is the granddaughter of K" derived from "K + L $ M @ N", is definitively true based on the given coding rules.

Revision Table: Blood Relation Summary

Additional Information on Blood Relation Problems

Blood relation problems are common in reasoning sections of competitive exams. They test your ability to decode relationships from symbols or phrases and construct a family tree or diagram mentally or on paper. Key aspects to remember:

• Pay close attention to the gender of individuals specified by the codes.
• Track relationships step-by-step from one person to the next.
• Be careful about implied relationships versus explicitly stated ones.
• Sometimes the gender of a person might not be specified by their role (e.g., P is a parent of Q, but P's gender is unknown unless another code clarifies it).
• Practice drawing family trees to visualize the relationships, especially for complex codes.