"It’s exciting to be in the same room as the _______," Miller said

A. President
B. U.S. president
C. U.S. President
D. president

Wouldn't both A and C work?

Yes, both A and C would work. The capitalization of "President" is a style preference, but both options refer to the same person and title.

Yes, both options A ("President") and C ("U.S. President") would work in the given sentence. Both of them refer to the highest elected official of the United States. The choice between using "President" or "U.S. President" depends on the context in which the statement is made. Option B ("U.S. president") is grammatically incorrect because "president" should not be capitalized unless it is part of a proper noun or title. Option D ("president") is also correct, but it is less specific as it does not specify if it is referring to the President of the United States or any other president.