Observe the following incomplete letter sequence carefully. A specific pattern governs the order and repetition of the letters. Choose the option that best fills the blanks to complete the sequence logically and symmetrically. ab_dcb_ab_dc_a
Show answer & explanation
Correct answer: D
Explanation
Given Series:
ab_dcb_ab_dc_a
Split into equal clusters (7–7 letters)
ab_dcb_ | ab_dc_a
Pattern: Each cluster follows a continuous sequence of letters:
a → b → c → d → c →b → a (i.e., abcdcba)
So, missing letters in series are:
c, a , c , b .
Hence, the correct answer is option 4.