AMC 12A 2015 Problem 12

The parabolas y=a x^{2}-2 and y=4-b x^{2} intersect the coordinate axes in exactly four points, and these four points are the vertices of a kite of area 12 . What is a+b ?

Answer Choices
A. 1
B. 1.5
C. 2
D. 2.5
E. 3