A particle of mass $$m$$ is dropped from a height $$h$$ above the ground. At the same time another particle of the same mass is thrown vertically upwards from the ground with a speed of $$\sqrt{2gh}$$. If they collide head-on completely inelastically, the time taken for the combined mass to reach the ground, in units of $$\sqrt{\frac{h}{g}}$$ is

A

$$\sqrt{\frac{1}{2}}$$

B

$$\sqrt{\frac{3}{4}}$$

C

$$\frac{1}{2}$$

D

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