Letter protocol

I wrote an email to a recruiting agent (C) regarding an employment positon. I have received a response from (C) on behalf of another more senior person(A) in the department with (A's ) title and contact information. The agent (C) has copied (A) as well as another person - whose role remains a mystery at this stage, but who must also be senior to (C) - with his response to me thanking me for my interest and asking that I give them a convenient time to conduct an interview with me. To whom am I exoected to reply??? Thank you.