Question

Assertion (A): Hemichordata is now placed as a separate phylum under non-chordata.
Reason (R): The stomochord of these animals was once believed to be the notochord.

• A. Both A and R are correct and R is the correct explanation of A.
• B. Both A and R are correct but R is not the correct explanation of A.
• C. A is correct but R is incorrect.
• D. A is incorrect but R is correct.

Hint:

Hemichordates lack a true notochord—stomochord is not homologous to it.

Answer 1

The Correct Option is B

Hemichordata was once grouped under chordates due to the presence of a structure called the stomochord. It was later found to be different from a true notochord, leading to its reclassification under non-chordata. So, both A and R are true but R is not the reason for the current classification.