While comparing invertebrate groups, a clam protects its soft body with left and right valves joined by a hinge ligament. The feature being tested is:

Correct Answer: B

two hinged shells

Bivalves possess two shell valves joined dorsally by a hinge. They include clams, mussels, oysters, and scallops. This MCQ belongs to the Bivalvia topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.