The Health Professionals Cohort Study began in 2005 in order to evaluate a series of hypotheses about men's health relating nutritional factors to the incidence of serious illnesses such as cancer, heart disease, and other vascular diseases. Every two years, members of the study will receive surveys with questions about diseases and health-related topics like smoking, physical activity, and medications taken. The surveys that ask detailed dietary information will be administered in four-year intervals. What kind of cohort study is this?
a. Retrospective
b. Prospective
c. Ambidirectional

b. Prospective cohort study

Explanation:

Prospective cohort study -

It is a type of cohort study, which require certain period of time to get the result on a group of similar or equivalent peoples, that shows variation on certain factor, which is studied, is referred to as the prospective cohort study .

The time period for such studies usually varies from several months to years, in order to get the result in a very precise and brief manner .

The studies can be done on various topics like smoking habits , alcohol consumption, sleep cycle, diseases etc.

Hence, from the given scenario of the question,

The survey asking for dietary intake , is an example of the prospective cohort study.