Soft-Shell Crab Is a Prized Dish in Many Ocean-Side Resorts

Multiple Choice

Soft-shell crab is a prized dish in many ocean-side resorts. Which of the following statements provides the best explanation for the soft shell of the crabs?

A) The crab has just molted and the new exoskeleton has not yet hardened.
B) These species of crabs live under rocks and therefore have lost the hard exoskeleton over evolutionary time.
C) These species have evolved a light and soft exoskeleton so that gases can diffuse directly between body of the crab and the surrounding water.
D) These species have evolved a light and soft exoskeleton so that they can float in the water column.