Surveys of the population to estimate the prevalence of a disease or exposure are which type of study?

Descriptive research

Explanation:

If our goal is to estimate the prevalence of a disease or exposure in a population, we are talking about descriptive research. Whenever we are trying to describe the characteristics of a population or a phenomenon (in this case the frequency of a disease and exposure to it) we are doing a descriptive study. The results of this type of studies are usually represented in descriptive statistics and percentages. For example, from this sort of survey we would find out the percentage of population that suffer this disease.

answer; i believe the correct answer is (a) the correlation between the cause variable and outcome variable is zero;

i truly dont know the answer wait i do its 1,3,4