Two ships A and B are sailing straight away from a fixed point O along routes such that $\;\angle{AOB}\;$ is always $\;120^{0}\;$ . At a certain distance , OA=8 km ,OB=6 km and the ship A is sailing at the rate of 20 km/hr while the ship B sailing at the rate of 30 km/hr . Then the distance between A and B is changing at the rate ( in km/hr ) :

Question

$(a)\;\large\frac{260}{\sqrt{37}} \qquad(b)\;\large\frac{260}{37} \qquad(c)\;\large\frac{80}{\sqrt{37}} \qquad(d)\;\large\frac{80}{37} $