A major role for Executive Departments is:
C) Protecting the public welfare.
The executive departments are the primary unit of the executive branch of the Federal Goverment of the United States, led by the Head of State (the President). These departments are the administrative arms of the President and each one's head has the title of Secretary of their respective department.
There are 15 executive departments' secretaries forming the Cabinet and their role is to advice the President. The latter has the right to choose his Cabinet members and they are aproved by the Congress. They act as external advisors and are in the line of succesors if anything happens to the President.