A Cable Railway Had a 12-Foot-Diameter Pulley to Drive the Cable

Multiple Choice

A cable railway had a 12-foot-diameter pulley to drive the cable (see the figure) . In order to keep the cable cars moving at a linear velocity of 9 miles per hour, how fast would the pulley need to turn (in revolutions per minute) ? (1 mi = 5,280 ft) ​ ​

A) 23.2 rpm
B) 24.5 rpm
C) 15.3 rpm
D) 28.1 rpm
E) 21.0 rpm