An example of a cabinet department is the a) central intelligence agency b) food and drug administration c) postal regulatory commission or d) office of health and human services?

The correct answer is: The office of Health and Human Services (more properly known as the United States Department of Health and Human Services).

The other options present agencies, not cabinet departments. Agencies are parts of the Cabinet Departments, for example the Food and Drug Administration is part of the Department of Health and Human Services.