Give a brief description of the factors involved in understanding the etiology of a disease.

Relatedly, when disease is widespread, epidemiological studies investigate what associated factors, such as location, sex, exposure to chemicals, and many others, make a population more or less likely to have an illness, condition, or disease, thus helping determine its etiology.  

Location, sex, and exposure to chemicals make a population more or less likely to have an illness. This helps determine the etiology when the disease is widespread.

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.

a physical change is being made.