The given problem involves the interpretation of Hammett plots corresponding to Reaction M and Reaction N. The Hammett plot helps us understand the electronic effects of substituents on reaction rates.

In Hammett plots, the substituent constant \sigma indicates whether the substituent is electron-donating or electron-withdrawing. A positive \sigma indicates electron-withdrawing, and a negative \sigma indicates electron-donating properties.

Let's match the points on the graph:

Reaction M:

• u: The point has a negative \sigma value, indicating electron-donating substituents. Hence, it matches with NH_2, which is strongly electron-donating.
• p: It is closer to zero on the negative side, indicating a weak electron-donating substituent. Thus, it matches with Me.
• t: This point has a slightly negative \sigma value than Me, thus correspond with OMe.

Reaction N:

• q: Near the positive \sigma value, indicating strong electron-withdrawing capability, matches with CN.
• r: Even more positive, aligning with a very electron-withdrawing nature, matches with NO_2.
• s: Positive but less than NO_2, matches with moderately electron-withdrawing Cl.

Based on the above reasoning:

1. Option 1: Matches with the correct assignment for s, t, u, and r.
2. Option 3: Matches with the correct assignment for p, q, r, and t.

Therefore, the correct answers are:

• s \to \sigma(X = Cl); t \to \sigma(X = OMe); u \to \sigma(X = NH_2); r \to \sigma(X = NO_2)
• p \to \sigma(X = Me); q \to \sigma(X = CN); r \to \sigma(X = NO_2); t \to \sigma(X = OMe)