A Spool Whose Inner Core Has a Radius of 1

Multiple Choice

A spool whose inner core has a radius of 1.00 cm and whose end caps have a radius of 1.50 cm has a string tightly wound around the inner core. The spool is free to roll without slipping on a horizontal surface. If the string unwinds horizontally from the bottom of the core with a constant speed of 25.0 cm/s, what is the speed of the spool?

A) 5.00 cm/s
B) 15.0 cm/s
C) 25.0 cm/s
D) 37.5 cm/s
E) 75.0 cm/s