From the given options, select the group of letters that, when inserted in order from left to right into the blanks of the incomp…

Question

From the given options, select the group of letters that, when inserted in order from left to right into the blanks of the incomplete series, will logically complete it. cdfcefcdefcdecdefcdecdef

1. A. fcde
2. B. cddf
3. C. efdf
4. D. edff (Correct answer)

Correct Answer

Option D — edff

Detailed Solution & Explanation

The correct answer is edff.

Key Points

• The series repeats the block cdef. Writing it in groups of four:
  • c d _ f | c _ e f | c d e f | c d e _ | c d e f | c d e _ | c d e f
• Filling each gap against the pattern:
  • block 1 needs e, block 2 needs d, block 4 needs f, block 6 needs f
• Reading left to right: e, d, f, f = edff.

Additional Information

• The first step is always to find the block length by looking for the first repeated run — here the recurring "cdef" gives 4, and the total length of 28 confirms exactly 7 blocks.
• Dividing the string into blocks on paper before filling anything turns the question into simple pattern matching.
• Answer the blanks strictly left to right, since the options are ordered sequences; the right letters in the wrong order is the standard distractor.
• Common block lengths in this format are 3, 4 and 5, so test those first.