Which situation can be modeled by the equation y=mx+b?
A. The number of members (y) in a club triples every year (x).
B. The volume (y) of a square prism with a height of 4 inches depends on the side length (x) of its square base.
C. The total cost (y) of hiring an electrician who charges 60 dollars per hour depends on the number of hours (x) he works.
D. The time (y) it takes to type a 50 words depends on the number of words typed per minute (x).