A monochromatic source emitting radiation with a certain frequency moves with a velocity v away from a stationary observer A. It is moving towards another observer B (also at rest) along a line joining the two. The frequencies of the radiation recorded by A and B are VA and VB, respectively. If the ratio \(\frac{{{{\rm{V}}_{\rm{B}}}}}{{{{\rm{V}}_{\rm{A}}}}}\) = 7, then the value of v/c is
1
1/2
2
1/4
3
3/4
4
\(\sqrt 3 /2\)