In the letter pair series WD, SH, OL, which of the following pairs correctly completes the pattern as the next term?

Introduction / Context:
This question presents a series of two letter pairs: WD, SH, OL, followed by a missing pair. The goal is to identify the consistent pattern in both the first and second letters of each pair and apply it to find the next pair. These types of letter pair series are standard in logical reasoning sections and usually rely on fixed increments or decrements in alphabet positions.

Given Data / Assumptions:

• Given pairs: WD, SH, OL, ?
• Alphabet positions: W 23, S 19, O 15, D 4, H 8, L 12.
• We must identify the next pair from JQ, KP, PK, LM, KR.

Concept / Approach:
We treat the first letters of each pair as one sequence and the second letters as another sequence. Then we convert these letters to positions and inspect how they are changing. If we see a constant step, either positive or negative, we can extend that step to find the next letter in each sequence. Finally, reassemble these letters into a pair and match it with the options.

Step-by-Step Solution:
Step 1: Convert the first letters to positions: W is 23, S is 19, and O is 15. Step 2: Compute the differences: 23 to 19 is minus 4, and 19 to 15 is minus 4. So the first letters decrease by 4 each time. Step 3: Continue this pattern. Subtract 4 from 15 to get 11, which corresponds to the letter K. Step 4: Now convert the second letters: D is 4, H is 8, and L is 12. Step 5: Compute the differences: 4 to 8 is plus 4, and 8 to 12 is plus 4. So the second letters increase by 4 each time. Step 6: Continue this pattern for the second letters. Add 4 to 12 to get 16, which corresponds to the letter P. Step 7: Combining the next first letter K and the next second letter P, we get the pair "KP".

Verification / Alternative check:
Write out the full pattern with numeric positions: WD (23,4), SH (19,8), OL (15,12), KP (11,16). We see that the first component goes 23, 19, 15, 11, each step minus 4. The second component goes 4, 8, 12, 16, each step plus 4. This clean pair of arithmetic sequences in opposite directions confirms that "KP" is the correct continuation of the series. None of the other options fits both the decreasing first letters by 4 and the increasing second letters by 4 simultaneously.

Why Other Options Are Wrong:
"JQ" would require the first letter J (position 10), which is minus 5 from O instead of minus 4, and a second letter Q (position 17), which is plus 5 from L instead of plus 4.
"PK" inverts the pattern, giving first letter P (16) and second letter K (11), which does not match the predicted next steps of 11 and 16.
"LM" has letters that do not align with the required positions of 11 and 16 for the next step.
"KR" uses K correctly in the first position but R is 18, giving an increase of +6 from L, which breaks the constant plus 4 rule in the second position.

Common Pitfalls:
One common mistake is to focus on only one position, for example noticing that first letters move backwards, but ignoring the second letters. Another trap is to guess by rough visual similarity, for instance, choosing LM because it appears near the previous pair, without checking numeric positions. A disciplined approach always examines both letters in the pair and maintains the same arithmetic pattern for each component.

Final Answer:
The pair that correctly completes the series is KP.