Roger is studying how energy from the sun changes to chemical energy in plants and to mechanical energy in animals. he is studying

Thermodynamics

Explanation:

Thermodynamics is the branch of physics that deals with the heat and temperature, work, changes in the form of energy.

The change in the form of energy is also studied under this subject. The change in the form of energy from light energy to chemical energy occurs in the process of thermodynamics.

Hence, the correct answer is Thermodynamics.

there's the proffessional site that will you.

carbon atoms, hydrogen, oxygen, and nitrogen.