A baseball of mass m = 0.49 kg is spun vertically on a massless string of length l = 0.73 m. The string can only support a tension of t_max = 8.7 N before it will break. What is the maximum possible speed of the ball at the top of the loop, in meters per second?

a) 7.5 m/s
b) 8.2 m/s
c) 9.1 m/s
d) 9.9 m/s