Select and write the correct answer from the given alternative in the following:If `x gt 0`, `y gt 0` and `xy<1` then `tan^-1x+tan^-1y = ..........` A) `tan^-1(frac{x+y}{1-xy})` B) `tan^-1(frac{x-y}{1+xy})` C) `frac{pi}{2}` D) `pi+tan^-1(frac{x+y}{1-xy})`

Options

A. `tan^-1(frac{x+y}{1-xy})`
B. `tan^-1(frac{x-y}{1+xy})`
C. `frac{pi}{2}`
D. `pi+tan^-1(frac{x+y}{1-xy})`