Epidemiology is defined as the study of1. Epidemiology 2. where a disease occurs. 3. how a disease is transmitted. 4. when a disease occurs. 5. where and when a disease occurs, and how it is transmitted.

5). where and when a disease occurs, and how it is transmitted.

Explanation: Epidemiology is a branch of medicine and the cornerstone of public health that studies the distribution and control of a disease. Epidemiology involves the study of who is affected by a disease, where is affected (the geographical location), when it is affected (time) and the used of these studies in the control of diseases and other health problems.

currents is the correct answer.

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."