Logical Sequence

Concept: Such questions are based on pattern continuation and symmetry in letter sequences. Step 1:Analyze the structure:
Step 2:Observe repeating patterns:

• Segments like dba, bcad, da, cd
• Suggest a structured progression using letters a, b, c, d

Step 3:Try option (D)} abcddcba: Insert sequentially: This creates a consistent and symmetric pattern using all letters.
Step 4:Other options do not maintain proper order or symmetry.}
Step 5:Final Answer: