The correct equation to find the total number of contestants, \( C \), that audition in \( h \) hours is:
A. \( C = 50h \)
This equation represents the fact that 50 contestants audition each hour for \( h \) hours, so to find the total, you multiply the number of contestants per hour (50) by the number of hours (h).
So the correct answer is A. \( C = 50h \).