You Are Working at the Reception Desk and Are on the Phone

You are working at the reception desk and are on the phone when Mr. Tomas arrives. What should you do?

A) Continue with the phone call, knowing you will be with him in a few minutes.
B) Continue with the phone call and acknowledge Mr. Tomas with a smile and eye contact.
C) Put the caller on hold and greet Mr. Tomas.
D) Tell the caller you will call him back and then greet Mr. Tomas.