Final answer:
The executive branch of the federal government is responsible for the administration of policy, which includes enforcing laws and managing the implementation of policies through federal agencies.
Step-by-step explanation:
The activity of the executive branch of the federal government primarily involves the administration of policy. This branch, led by the President, is responsible for enforcing laws and is also involved in the creation and management of agencies that implement policies, particularly after those policies have been enacted by the legislative branch.
The President does play a role in proposing policy during events like the State of the Union Address and may offer a legislative agenda, but the actual enactment and passage of policy fall within the jurisdiction of Congress. Similarly, the interpretation of policy is mainly the domain of the judicial branch. Therefore, the correct answer to the student's question is a. Administration of policy.