**Core Concept**
The systematic study of human disease and social conditions/factors is a multidisciplinary field that examines the interplay between biological, psychological, and social factors contributing to disease and health outcomes. This field aims to understand how social determinants of health, such as socioeconomic status, education, and environmental exposures, influence disease susceptibility and health disparities.

**Why the Correct Answer is Right**
The correct answer is **Epidemiology**, which is the study of the distribution and determinants of health-related events, diseases, or health-related characteristics among populations. Epidemiologists use statistical methods and research designs to identify risk factors, understand disease patterns, and develop interventions to prevent and control disease. Epidemiology is essential in understanding the social and environmental factors that contribute to disease and in developing effective public health strategies.

**Why Each Wrong Option is Incorrect**
* **Option A:** Pathology is the study of the causes and effects of diseases, but it focuses primarily on the biological and histopathological aspects of disease rather than the social and environmental factors.
* **Option B:** Biostatistics is the application of statistical methods to understand and analyze health data, but it is a separate field from epidemiology and does not focus on the social and environmental determinants of health.
* **Option C:** Public Health is a broader field that encompasses the prevention and promotion of health, but it is not a specific field of study that focuses on the systematic study of human disease and social conditions.
* **Option D:** Preventive Medicine is a medical specialty that focuses on preventing and controlling disease, but it is not a specific field of study that examines the social and environmental determinants of health.

**Clinical Pearl / High-Yield Fact**
Epidemiology is essential in identifying health disparities and developing targeted interventions to address them. The study of epidemiology has led to numerous public health successes, including the eradication of smallpox and the control of infectious diseases such as polio and measles.

**Correct Answer: Epidemiology. Epidemiology**