Two satellite \( A \) and \( B \) go round a planet in circular orbits having radii \( 4R \) and \( R \) respectively. If the speed of \( A \) is \( 3v \), the speed of \( B \) will be;
\( 3v \)
\( 12v \)
\( \displaystyle\frac{4}{3}v \)
\( 6v \)