Two sources `S_1` and `S_2` of sound having frequencies `338`Hz and `342 `Hz are separated by a large distance. The speed of sound is `340` ms^(-1). With what velocity should an observer move from source `S_2 to S_1` so that he hears no beats?

Options

A. `1 ms^(-1)`
B. `2 ms^(-1)`
C. `3 ms^(-1)`
D. `4 ms^(-1)`