While comparing invertebrate groups, a lecturer explains why arthropod legs can move powerfully despite being externally armored. The feature being tested is:

Correct Answer: D

exoskeleton provides muscle attachment

The arthropod exoskeleton provides protection and points for muscle attachment. Muscles attach internally to the exoskeleton and move jointed appendages efficiently. This MCQ belongs to the Arthropoda topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.