Latent heat involves

A. the conversion of radiant energy into energy that can be felt by people.
B. the conversion of radiant energy into "hidden" form through the process of evaporation.
C. the reflection of radiant energy in the atmosphere back out to space.
D. the conversion of longwave radiation at the surface to shortwave radiation in the atmosphere.

the conversion of radiant energy into "hidden" form through the process of evaporation.

Explanation:

Latent heat is the heat which is stored in the molecular motion of  any substance when it changes its state, Like from solid to liquid, solid to gas or liquid to gas. It is also known as hidden heat.

Example: when water changes its state from water  to water vapor, water absorbs energy from the environment. This energy is stored in the molecular movement of water molecules.

On earth, latent heat is transferred when there is evaporation of water from moist land surface or any water body. This causes transfer of heat from earth surface to atmosphere.  

Bases on the above definition of latent heat option B is the correct one.