A man in a boat rowing away from the cliff 150 meters high, observed that it takes 2 minutes to change the angleofelevation of the top of the cliff from $$60^\circ$$ to $$45^\circ$$, then the speed of the boat in km/hour is

A

$$\frac{9 - 3\sqrt{3}}{2}$$

B

$$\frac{9 + 3\sqrt{3}}{2}$$

C

$$9 - \sqrt{3}$$

D

$$9 + \sqrt{3}$$