JEE Math Practice Question

If e1 and e2 are the eccentricities of the ellipse, $${{{x^2}} \over {18}} + {{{y^2}} \over 4} = 1$$ and the hyperbola, $${{{x^2}} \over 9} - {{{y^2}} \over 4} = 1$$ respectively and (e1, e2) is a point on the ellipse, 15x2 + 3y2 = k, then k is equal to :

1. A.17
2. B.16
3. C.15
4. D.14