A company is paying a local television station to run its commercials. The cost for running commercials is a one-time campaign fee and also a per-second fee for the air time of each commercial. The cost can be modeled by the equation y = 500 + 50x where x is seconds.
What is the y-intercept and what does it represent?

A. 500; it represents the per-second fee of air time

B. 500; it represents the one-time campaign fee

C. 50; it represents the per-second fee of air time

D. 50; it represents the one-time campaign fee