What is a disadvantage for populations of organisms living in water? 

A)  less exposure to UV radiation 
B)  exposure to dissolved pollutants 
C)  physical support from water buoyancy 
D)  fairly constant temperature

UV Radiation

Ultraviolet radiation is a form of energy traveling through space, emitted by the sun, and has shorter wavelengths than visible light, capable of causing skin damage.

Dissolved Pollutants

Substances that are fully dissolved in water, making them particularly difficult to remove from aquatic environments.

Water Buoyancy

The ability or tendency of an object to float in water or another fluid, determined by the object's density relative to that of the fluid.