Echinoderms . Select one: a. have an exoskeleton of hard calcareous plates b. often use tube feet to move around in their environment c. digest their food outside of the organism d. circulate hemolymph in their water vascular system e. are most often found in freshwater environments

B. often use tube feet to move around in their environment

Explanation:

Tube feet are tiny tubular projections of echinoderms on the underside (oral side). They are a member of the echinoderm water vascular system.

Tubular feet are used for feeding, breathing and shifting. They are arranged around the sides, in grooves. They work by hydraulic pressure. They are used to transfer food in the centre to the oral mouth, and may stick to surfaces. Tube feet allow certain animals to stick and travel slowly to the ocean floor. for example starfish uses tube feet for the above functions.

Hence, the correct option is B.

answer; the tunica intima also called tunica interna, consists of elastic fibers,connective tissue and smooth muscle cells;