In a specimen-based viva, the examiner describes this case: a crab exchanges gases using feathery structures associated with appendages under the carapace. Choose the concept that fits it best.

Correct Answer: A

gills

Aquatic crustaceans generally respire by gills. These structures are adapted for extracting dissolved oxygen from water. This MCQ belongs to the Crustacea topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.