Two parabolas C and D intersect at two different points, where C is y=x2−3 and D is y=kx2 . The intersection at which the x value is positive is designated point A, and x=a at this intersection the tangent line l at A to the curve D intersects curve C at point B, other than A. If x-value of point B is 1, then a is equal to
a. 1
b. 2
c. 3
d. 4