The shellthe shell the footthe foot the mantlethe mantle the visceral massthe visceral mass gillsgills the radulathe radula the open circulatory systemthe open circulatory system

a) true

b) false

Answer & explanation:

Gills are an adaptive structure for fish and other aquatic animals to survive in the aquatic environment.

They are blade-shaped and highly vascularized, allowing gas exchanges between the ambient water and the animal's blood.

Water enters the mouth and is led through the gills, being eliminated by gill slits, then oxygen is distributed in the blood to the animal's body.