If all the letters in the word MERCIFUL are first rearranged in alphabetical order and then each letter is replaced by the letter immediately preceding it in the English alphabet, what will be the resulting new arrangement of letters?

Introduction / Context:
Alphabet rearrangement questions combine two or more operations on letters. They are very popular in competitive exams because they test both attention to detail and the ability to follow rules in sequence. In this problem, the word MERCIFUL must first be rearranged in alphabetical order, and only then must each letter be shifted to the immediately preceding letter in the alphabet. Understanding the order of operations is crucial for arriving at the correct final arrangement.

Given Data / Assumptions:
- The original word is MERCIFUL.
- We must rearrange all its letters in alphabetical order.
- After rearrangement, each letter is replaced by the letter that comes just before it in the English alphabet.
- No letters are added or removed; only their order and identity change according to the rules.

Concept / Approach:
The solution involves two clear steps. First, sort the letters of MERCIFUL in ascending alphabetic order. Second, transform every letter in this sorted sequence by shifting it backward by one position in the alphabet. It is important not to mix the order of these operations. Sorting first and then substituting will give a different result than substituting first and then sorting. The question explicitly states the sequence, so following it carefully is essential.

Step-by-Step Solution:
Step 1: Write the letters of MERCIFUL: M, E, R, C, I, F, U, L. Step 2: Arrange these letters in alphabetical order: C, E, F, I, L, M, R, U. Step 3: Replace each letter by the one immediately preceding it in the alphabet: C becomes B, E becomes D, F becomes E, I becomes H, L becomes K, M becomes L, R becomes Q, U becomes T. Step 4: Collect the new letters in order: B D E H K L Q T. Step 5: Without spaces, this new arrangement is BDEHKLQT, which matches option B.

Verification / Alternative check:
To verify, repeat the backward shift process separately: note that each new letter should be exactly one position earlier in the alphabet than its original. C is followed by D in the alphabet, so moving backward gives B. Similarly, E moves to D, F to E, I to H, L to K, M to L, R to Q, and U to T. Confirming each shift ensures that no letter is incorrectly transformed. Finally, confirm that sorting MERCIFUL alphabetically indeed gives CEFILMRU.

Why Other Options Are Wrong:
- "BDHEKLQT" and "BDEHLKQT" differ in the relative positions of letters like H, K, and L, showing that the sorting or shifting was not applied correctly.
- "BDEJMLQT" contains J and M, which do not follow from shifting I and N correctly in the actual sequence of this word.
Only "BDEHKLQT" corresponds to the correct sequence of sorted letters and properly shifted substitutions.

Common Pitfalls:
Candidates may mistakenly apply the letter shift first and then sort, which leads to a completely different arrangement. Another source of error is forgetting that each letter moves backward by exactly one position, not forward. Finally, careless alphabetical sorting of the original word MERCIFUL may introduce mistakes that will be carried into the transformation stage. Working slowly through each step and checking the sorted sequence before shifting helps avoid these errors.

Final Answer:
The correct new arrangement of letters after sorting and shifting is BDEHKLQT.