Question

A series is given with some letters missing. Choose the set of letters which when sequentially placed shall complete it:
a__ dba __ bcad __ da __ cd}

• A. cbcdcba
• B. bccdbcab
• C. aabbccdd
• D. abcddcba

Hint:

Look for \textbf{mirror patterns} or \textbf{alphabet sequences} (like abcd, dcba) in such problems.

Answer 1

The Correct Option is D

Concept: This is a pattern completion problem based on structured symmetry and repeated letter grouping in a sequence. Step 1:Analyze the given structure.
\[ a__\; dba\; __\; bcad\; __\; da\; __\; cd \]
Step 2:Identify the pattern behavior.
The sequence is built using recurring blocks of letters:

• dba
• bcad
• da
• cd

These indicate a structured arrangement of the letters a, b, c, d in a cyclic symmetric form.
Step 3:Test option (D): abcddcba.
Placing the pattern into the blanks produces a continuous symmetric flow: \[ a\underline{bc}dba\underline{dd}bcad\underline{cb}da\underline{a}cd \] This maintains both repetition and mirror symmetry across the sequence.
Step 4:Check alternatives.
Other options fail to preserve consistent symmetry or disrupt the repeating block structure.
Final Answer: abcddcba