Choose the best answer to the following.In Europe, alternating electric current vibrates t...

Choose the best answer to the following.

In Europe, alternating electric current vibrates to and fro 50 cycles in 1 s. The frequency of these vibrations is

(a) 50 Hz with a period of

(b)  with a period of 50 s.

(c) 50 Hz with a period of 50 s.

(d)  with a period of