**Core Concept**
The question is testing the definition of a field of study that focuses on understanding human behavior, relationships, and life patterns. This field is closely related to psychology, sociology, and anthropology, but with a broader scope.

**Why the Correct Answer is Right**
The correct answer, **Demography**, is a field that studies the characteristics of populations, including their size, structure, and distribution. It examines the patterns of human life, including birth rates, death rates, marriage rates, and migration patterns. Demography uses statistical methods and data analysis to understand the dynamics of human populations and their relationships. This field is essential for understanding the social and economic implications of population growth and changes.

**Why Each Wrong Option is Incorrect**
**Option A:** Demography is not the study of human behavior, but rather the study of population characteristics.
**Option B:** This option is not a valid field of study related to human relationships and behavior.
**Option C:** This option is a related field, but it is more focused on the study of human behavior and mental processes, rather than population characteristics.

**Clinical Pearl / High-Yield Fact**
Demography is a crucial field for public health policymakers, as it helps them understand the needs and trends of populations, making informed decisions about resource allocation and policy development.

**Correct Answer:** C.