Study the following letter sequence: A A B A B C A B C D A B C D E A B C D __. Which letter should come next in place of the blank to continue the pattern correctly?

Introduction / Context:
This is a letter sequence question where you must recognise the underlying pattern and then extend it correctly. Alphabet test problems like this are designed to check how quickly you can observe repetition, grouping, and gradual growth in patterns, which is a common skill required in competitive examinations.

Given Data / Assumptions:
• The given sequence is: A A B A B C A B C D A B C D E A B C D __.
• All letters are from the English alphabet and appear in increasing order within certain groups.
• We need to identify the logical rule that generates this sequence and find the missing letter that should follow D at the end.

Concept / Approach:
The key idea is to look for grouping in the sequence rather than treating all letters as one long stream. Many such questions are constructed using blocks that repeat with a slight extension each time. By splitting the sequence into possible segments like A, A B, A B C, A B C D, and A B C D E, we can see an increasing pattern where each new group adds one more letter to the previous block.

Step-by-Step Solution:
Step 1: Rewrite the sequence with visual grouping: A / A B / A B C / A B C D / A B C D E / A B C D __.Step 2: Observe the pattern of groups: the first group has only A, the second group has A B, the third group has A B C, the fourth has A B C D, and the fifth has A B C D E.Step 3: Notice that each new group starts with A and adds one more letter in alphabetical order compared with the previous group.Step 4: The sequence shown near the end is A B C D forming the beginning of the next group. According to the pattern, this group should ultimately be A B C D E.Step 5: Therefore, the letter that must come after this final D is E, to complete the block as A B C D E.

Verification / Alternative check:
You can verify the pattern by counting group sizes. The group lengths are 1, 2, 3, 4, and 5. The last incomplete group has length 4 and obviously should become the next group of size 5. Since all such groups follow alphabetical order starting from A, the missing fifth letter in the last group must be E. This confirms E as the only consistent answer.

Why Other Options Are Wrong:
• A: If A were placed, the pattern of steadily growing groups would be broken because A B C D A would not fit the A to E progression.
• C: Repeating C at that point does not match the rule of adding the next new letter in the alphabet, which must be E.
• B: Adding B again would create A B C D B, which neither forms a standard alphabetical block nor matches the earlier structure.
• D: Repeating D would give two consecutive Ds and disturb the regular pattern of increasing groups, so it cannot be correct.

Common Pitfalls:
Many students try to see the pattern in consecutive letters only and miss out on the grouping idea. Others may think that the sequence is repeating A B C D, but that fails when you notice the earlier A B C D E block. A reliable strategy is to mark commas or slashes and ask yourself whether there is a progressive structure in the lengths of these blocks. Once that is done, such problems become straightforward.

Final Answer:
The letter that should come next to continue the given pattern correctly is E.