The professional military owes its first and foremost allegiance to the?

President of the United States

I, (NAME), do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; and that I will obey the orders of the President of the United States and the orders of the officers appointed over me, according to regulations and the Uniform Code of Military Justice. So help me God.

Your test is wrong the first loyalty belong to the Constitution of the United States and MUST bear true faith and Allegiance to the same.

Under the Uniform Code of Military Justice no one must follow an illegal order even if it comes from the President of the United States. If the President orders the Military to do a house to house search and seize all firearms this would be an illegal order because the US Constitution's 2nd Amendment allows all people to keep and bear arms.

Constitution first

(I [state your name] do solemnly swear [or affirm] to support and defend the Constitution of the United States of America, bearing true faith and allegience to the same without reservation or purpose of evasion; and further to obey all LAWFUL orders from the President...),

after that to obey all orders from the President or such officers (including the JCS) as are appointed under him.

The limiting language that only LAWFUL orders are to be obeyed puts the Congress and Courts in the mix.

As all Americans, the military owes its loyalty to the Constitution and to all officers appointed over them. The caveat of course is that no member of the armed services is required to obey an unlawful order. As I recall from my service days we actually had classes as to what was lawful and what was not. So far this system has prevented any military coups as any order that is unlawful would not be obeyed, and if obeyed would put those people involved in legal jeopardy.

Constitution; I concurred. The military shall defend the US Constitution and protect it from the government that could be tyrannical.The Constitution protect us from our own government, from each others, and foreign or domestics enemies.

People of the United States of America

I would say the Constitution, which is unfortunately not an option.

Usually any military's allegiance is to it's government. Very rarely do any actually take oaths to defend the people.

Geneva Conventions

General, and then constitution if it exists