Its option 2, Simple, lets take the circles as C1 and C2. C1=x^2+y^2-x=0. radius=1/2 and centre=(1/2,0). C2=x^2+y^2+x=0 radius=1/2 and centre=(-1/2,0). So, now we know the radius of both the circles and their centres. if r1+r2=distance between the centres, then the circles touch each other at one point and hence we can draw only 2 tangents. Here we observe the same, the distance between the two centres is 1 unit, and the sum of their radius is also 1 unit. Hence they touch each other at a point and hence only 2 tangents can be drawn.