[单选题]
A generator coil rotat5d)9 totxaauzrd)bslj9 1p )v :eg1 1yes through 60 o75 q,9wg4z5gfcnl icvl x4n1revolutions each second. The frequency of thc9xgfn n zw5io c44,lq51glv7 e $emf$ is
A. 30 Hz.
B. 60 Hz.
C. 120 Hz.
D. cannot be determined from the information given.
