Concept:
Psychology is the scientific study of human behavior and mental processes.
It explains:
• How people think
• How they feel
• Why they behave in certain ways
Psychology helps in understanding individual and social behavior.
Step 1: Analyze option A.
A social survey is a method of collecting information from people and is not the study of behavior itself.
Hence, option A is incorrect.
Step 2: Analyze option B.
Public health deals with community health and disease prevention, not specifically with study of behavior.
Hence, option B is incorrect.
Step 3: Analyze option C.
Psychology is defined as the scientific study of human behavior and mental processes.
Hence, option C is correct.
Step 4: Analyze option D.
Social communication refers to exchange of information among people and is not the scientific study of behavior.
Hence, option D is incorrect.
Therefore, the correct answer is:
\[
\boxed{(C)\ \text{Psychology}}
\]