The equation of the plane that meets the coordinated axis at the points $A,B,C$ respectively so that the centroid of the $\Delta ABC$ is $(\alpha,\beta,\gamma)$ is ?

Question

$(a)\: \alpha x+\beta y+\gamma z=1 \\(b)\: \large\frac{x}{\alpha}+\frac{y}{\beta}+\frac{z}{\gamma}=3 \\(c)\: \large\frac{x}{\alpha}+\frac{y}{\beta}+\frac{z}{\gamma}=1 \\ (d) \:\alpha x+\beta y+\gamma z=3$