Final answer:
The Presidential power to act as chief executive of the federal government comes from constitutional provisions, excluding the provision stating the executive power will be vested in a president. The other constitutional provisions empower the President with specific executive powers.
Step-by-step explanation:
The Presidential power to act as chief executive of the federal government comes from all of the following constitutional provisions except the provision stating the executive power will be vested in a president (Option A). The Constitution explicitly states that the executive power shall be vested in a President of the United States of America, giving the President the authority to execute and enforce laws as the chief executive. The other options, B, C, D, and E, all provide constitutional provisions that empower the President with specific executive powers such as appointing heads of departments, ensuring the faithful execution of laws, requiring the heads of departments to report to the President, and serving as Commander-in-Chief of the armed forces.