Based on revolving field theory, the forward and backward frequencies of the rotor emf of a 4-pole, 50 Hz, single-phase induction motor when running at 1300 rpm in the same direction of the forward field are respectively

A

6.67 Hz, 93.33 Hz

B

107.69 Hz, 7.69 Hz

C

93.33 Hz, 6.67 Hz

D

7.69 Hz, 107.69 Hz