The implementation of foreign policy in the U.S. primarily falls to the president, who leads foreign relations and military decisions. Executive agencies aid this process, while Congress provides legislative support. Therefore, the correct answer is A: the president.
;
The implementation of foreign policy in the U.S. is primarily carried out by the president, who has the authority to make significant decisions in foreign affairs. While executive agencies assist in this process and the armed forces may be involved, it is the president who ultimately has the responsibility. Congress plays a supportive role mainly in legislative matters related to foreign policy. ;