The United States Postal Service is an example of D. AN INDEPENDENT AGENCY OF THE EXECUTIVE BRANCH.
It has a Board of Governors who sets the policies, procedures, and postal rates of the United States Postal Service. 9 out of the 11 members of the Board are appointed by the President and confirmed by the Senate. The 9 members then appoint a 10th member, the U.S. Postmaster General who acts as CEO. These 10 members then appoint an 11th member, a Deputy Postmaster General who acts as the COO of USPS.