The area ( in square units) of the region enclosed by the two circles $x^2+y^2=1$ and $(x-1)^2+y^2=1$ is :

Question

$$\begin {array} {1 1} (1)\;\frac{2\pi}{3}+\frac{\sqrt 3}{2} & \quad (2)\;\frac{\pi}{3} +\frac{\sqrt 3}{2}\\ (3)\;\frac{\pi}{3}-\frac{\sqrt 3}{2} & \quad (4)\;\frac{2 \pi}{3}-\frac{\sqrt 3}{2} \end {array}$$