Sand , water , and minerals
D. i think if i get you wrong then I'm sorry
D.
Most of the marine animals have a stream lined body, which means, they have a sharp and pointed at the front. The pointed front of the organism allow to cut the resistance of the water. In case, the body is not pointed at the front and it is blunt, the water current and flow would resist the movement of the organism further. So, for the locomotion purpose, it is important to have a streamlined body. Further smooth and hair less body also decrease the resistance during the movement in the water.
C. identical to, different from
