A variable plane is at a constant distance $h$ from the origin and meets the co-ordinate axes in A, B, C. Locus of centroid of $\Delta ABC$ is :

Question

( A ) $x^2 + y^2 + z^2 = 4h^{-2}$
( B ) $\frac{1}{x^2} + \frac{1}{y^2} + \frac{1}{z^2} = \frac{9}{h^2}$
( C ) $x^2 + y^2 + z^2 = h^{-2}$
( D ) $x^2 + y^2 + z^2 = 16h^2$