The Ministry of Health in the Canadian Province of Ontario conducted the Ontario Health Survey by conducting interviews with 30,000 randomly selected men and 35,000 randomly selected women who reside in Ontario. This is an example of

Simple random sample

Explanation:

Simple random sample is a member of a sample selected from a larger population sample chosen at random in which every member has equal probability of being chosen. It is the unbiased representation of a group by its subset. Simple random sample is easily understood but difficult to perform.