Final answer:
The correct answer is that you were the 5th caller since the radio station played music for every fifth caller, and you were the first to win.
Step-by-step explanation:
Since the local radio station played music for one minute for every fifth caller, and you were the first to win both a music player and a concert ticket, you would have to be a caller that is a multiple of five. The only option that is a multiple of five and represents being the first caller to win is the 5th caller. Therefore, the correct answer is B. 5th caller.