Question

why do large animals, like hippos, spend much of their time in water? it reduces the effects of gravity. it reduces their mass. it increases their weight.

Explanation:

Large animals like hippos are heavy, so their bodies face significant gravitational stress on land. Water provides buoyancy, which counteracts gravity, reducing the strain on their bones and joints. Their mass and weight do not change in water—mass is an intrinsic property, and weight is gravitational force (unchanged unless gravity or mass changes). Buoyancy only lessens the effective weight they feel.

Answer:

It reduces the effects of gravity.