A block of mass $$m$$ is kept on a platform which starts from rest with a constant acceleration $$g/2$$ upwards, as shown in the figure. Work done by normal reaction on block in time $$t$$ is:

A

$$-\frac{mg^2t^2}{8}$$

B

$$\frac{mg^2t^2}{8}$$

C

0

D

$$\frac{3mg^2t^2}{8}$$