Hint: An epidemic disease means one that is transmitted in a particular area at a particular time. Usually such diseases are quite infectious or communicable and can be health-threat for every individual living in that area.
Complete answer: Any infectious or communicable disease which is transmitted in a particular area at a particular time is known as an epidemic disease. The study related to such diseases is known as epidemiology.
As a definition, epidemiology is a study which deals with the distribution & determinants of health related issues in specific populations.
In epidemiology, the patient is the community and individuals are viewed in a collective manner.
Additional information: The epidemiological study includes study of disease causative agents, its transmission, investigation of disease outbreak and its surveillance.
1. It has several branches like: environmental epidemiology, forensic epidemiology, occupational epidemiology etc.
2. It further includes screening, bio-monitoring, and comparisons of treatments i.e. effects of clinical trials.
3. Epidemiologists rely on biological sciences mostly for better understanding of the disease processes, causative agent’s life cycle.
4. They make use of statistics to bring appropriate conclusions.
5. They also involve social sciences to investigate proximate and distal causes.
So, the correct option is A. Epidemiology.
Note: Etiology is a branch of medical studies. It deals with the causes and origins of diseases. It may be considered a part of epidemiology.
Angiology is the study of the circulatory and lymphatic system.
Immunology is the study of the immune system and its development.