If Y = 002 Sin (30x - 400t)(SI Units),the Frequency of the Wave

Multiple Choice

If y = 0.02 sin (30x - 400t) (SI units) ,the frequency of the wave is

A) 30 Hz
B) 15/ $\pi$ Hz
C) 200/ $\pi$ Hz
D) 400 Hz
E) 800 $\pi$ Hz