The question asks us to find the combination of letters that completes the given series when placed in the blanks. This type of problem requires identifying the underlying pattern in the sequence.

Understanding the Series with Blanks

The given series is: TK _ TKT_ P_ K _ KPTK _ K _ TK

Let's count the total number of positions in the series, including the blanks. There are 14 letters and 6 blanks, making a total of $14 + 6 = 20$ positions.

The blanks are located at the following positions:

• Position 3
• Position 7
• Position 9
• Position 11
• Position 16
• Position 18

Strategy: Finding the Repeating Pattern

Letter series problems often follow a repeating pattern or a sequential rule. Since we are given multiple-choice options, the most straightforward approach is to test each option by filling the blanks and checking if a consistent pattern emerges.

Testing the Correct Option

Let's use the letters from the correct option (Option 3): P, K, T, T, T, P. We will place these letters sequentially into the blanks in the series.

• Blank 1 (Position 3) gets 'P'.
• Blank 2 (Position 7) gets 'K'.
• Blank 3 (Position 9) gets 'T'.
• Blank 4 (Position 11) gets 'T'.
• Blank 5 (Position 16) gets 'T'.
• Blank 6 (Position 18) gets 'P'.

Substituting these letters into the original series, we get:

T K P T K T K P T K T K P T K T K P T K

Identifying the Repeating Block

Now let's examine the completed 20-character series:

T K P T K T K P T K T K P T K T K P T K

Let's try dividing this series into segments. If we group the letters into blocks of 5, we see a clear repeating pattern:

• Segment 1 (Positions 1-5): T K P T K
• Segment 2 (Positions 6-10): T K P T K
• Segment 3 (Positions 11-15): T K P T K
• Segment 4 (Positions 16-20): T K P T K

The completed series is formed by repeating the block TKPTK exactly 4 times.

Verification

Let's verify that the letters we filled in match the expected letters from the repeating TKPTK pattern at the blank positions (3, 7, 9, 11, 16, 18).

• Position 3: Expected letter from TKPTK is 'P'. Filled letter is 'P'. Matches.
• Position 7: Expected letter from TKPTK (starting at position 6) is 'K'. Filled letter is 'K'. Matches.
• Position 9: Expected letter from TKPTK (starting at position 6) is 'T'. Filled letter is 'T'. Matches.
• Position 11: Expected letter from TKPTK (starting at position 11) is 'T'. Filled letter is 'T'. Matches.
• Position 16: Expected letter from TKPTK (starting at position 16) is 'T'. Filled letter is 'T'. Matches.
• Position 18: Expected letter from TKPTK (starting at position 16) is 'P'. Filled letter is 'P'. Matches.

All filled letters match the pattern, confirming that the sequence P, K, T, T, T, P correctly completes the series by forming the repeating block TKPTK.

Final Answer

The combination of letters that sequentially placed in the blanks of the given series completes the series is P, K, T, T, T, P.

Revision Table: Letter Series Analysis

Additional Information: Series Patterns

Letter series questions can involve various types of patterns. Some common types include:

• Alphabetic Order: Letters follow the standard alphabetical sequence, sometimes with skips (e.g., A, C, E, G...).
• Reverse Alphabetic Order: Letters follow the alphabet backward (e.g., Z, X, V, T...).
• Skipping Letters: Letters are skipped based on a fixed number or a varying number (e.g., A, C, F, J...).
• Repeating Blocks: A specific sequence of letters repeats throughout the series, as seen in this problem (e.g., ABCA BCA BC...).
• Combinations: The pattern might involve a combination of numbers and letters or alternating different types of letter patterns.
• Positional Value: Patterns based on the numerical position of letters in the alphabet (A=1, B=2, etc.).

Solving these requires careful observation and systematic testing of potential rules or repeating units.