A pair based alphabet series is given with one term missing. Select the correct alternative from the given options that will complete the series DE, HI, LM, ?

Introduction / Context:
This problem involves a sequence of two letter pairs where each pair consists of consecutive letters. The challenge is to examine how the starting and ending letters progress from one term to another and then determine the missing pair that follows the established pattern. These series questions are basic but important for building confidence in alphabet based reasoning.

Given Data / Assumptions:

• The sequence provided is DE, HI, LM, ?
• Each term is a pair of letters from the English alphabet.
• Positions: A = 1, B = 2, and so on up to Z = 26.
• We expect a consistent pattern when we move from one term to the next.

Concept / Approach:
We treat the first letters of each pair as one sequence and the second letters as another sequence. If a constant numerical increment is observed in both sequences, we can extend the pattern to find the next term. Alphabet series questions nearly always rely on simple arithmetic differences in positions when analysed this way.

Step-by-Step Solution:
Step 1: Look at the first letters: D, H, L. Their positions are D = 4, H = 8, L = 12. Step 2: Observe the differences: 4 to 8 is plus 4, and 8 to 12 is again plus 4. So we add 4 once more to 12. Step 3: 12 plus 4 equals 16, which corresponds to the letter P. So the first letter of the missing pair is P. Step 4: Now examine the second letters: E, I, M. Their positions are E = 5, I = 9, M = 13. Step 5: The differences are 5 to 9 is plus 4, and 9 to 13 is plus 4. So we add 4 again to 13. Step 6: 13 plus 4 equals 17, which corresponds to the letter Q. So the second letter of the missing pair is Q. Step 7: Hence, the missing pair is PQ.

Verification / Alternative check:
As a quick verification, notice that each pair consists of consecutive letters (D E, H I, L M, P Q) and that the starting letters form a simple plus 4 sequence: D, H, L, P. Similarly, the ending letters E, I, M, Q follow the same increment. This confirms that PQ maintains the established pattern in both positions.

Why Other Options Are Wrong:
QA and PR do not have both letters consistent with the plus 4 step from the previous pair. PR would require the second letter to be R, which does not align with adding 4 to M. PU also breaks the pattern because U is too far from M. Since PQ alone fits the numeric rule for both letters, all other options are incorrect. The none of these option is wrong because a valid pair PQ is already present among the options.

Common Pitfalls:
Students sometimes consider only the sequence of first letters and then guess a second letter that feels close but does not exactly match the pattern. Another trap is to overlook the fact that the pairs themselves are consecutive letters, which provides an additional clue. Taking the time to translate each letter into a numerical position usually clarifies the pattern and prevents guesswork.

Final Answer:
The pair of letters that correctly completes the series is PQ.