Ann said to me,"Have you ever been to United States?"
The two ways of relating what a person has said are 1)direct and 2)indirect (reported).
In the direct speech, the exact words of the original speaker are repeated.
In the indirect speech (reported speech), the exact meaning of what the speaker told is expressed but not necessarily in the speaker’s exact words.
Options C and D are correct as the question inside the inverted commas is transformed into an affirmative sentence using the past perfect tense (had) as the question is in the present perfect tense and uses the appropriate introductory verb (ask) in the past tense.
Options A and B are wrong as 'that' and 'told' cannot be used.
The correct answer is C)Ann asked me if I had ever been to the United States. and D)Ann asked me whether I had ever been to the United States.