Answer:
C. Optics
Step-by-step explanation:
We need to understand each of the fields first.
A. Thermodynamics: Thermodynamics is the branch of science the deals with the transfer of heat as it is clear from the name. Thermo means Heat and Dynamics means motion,
B. Quantum Mechanics: It is the study of the physical laws and properties in nature, at atomic or even sub-atomic level.
C. Optics: Optics is the branch of physics that deals with the nature of light light and the phenomena related to the light.
D. Electromagnetism: It is the branch of physics that deals with the interaction of electricity and magnetism.
Since, optics deals with the phenomena of light. Hence, person interested in how light passes through clear substances, should study:
C. Optics