What hard covering on the outside of some animals bodies

The word you're looking for is Exoskeleton. The outer covering is called an EXOSKELETON which is a hard covering on the outside of the body that provides both support and protection. The exoskeleton is made of CHITIN. Some exoskeletons are leathery like caterpillars, and some are tough and hard like ticks and crabs.

The correct answer is c

That is true tge cactus as a structural adaptation to its envirinment has it leaves reduced to spines. but this doesnt mean it cant produce food it produces food because of the presence of chlorophyll in its stem