An ellipsoidal cavity is carved within a perfect conductor (see figure). A positive charge q is placed at the centre of the cavity. The points A and B are on the cavity surface as shown in figure. Then, 

Change density at A < charge density at B. Since field inside cavity is zero, hence  Potential at A= potential at B = a constant value. By Gauss Theorem,
$\left(\begin{array}{l}Totalelectric\\ flux\end{array}\right)=\frac{1}{{\in }_0}\left(\begin{array}{l}ch\arg e\\ enclosed\end{array}\right)=\left(\frac{q}{{\in }_0}\right)$ 
Hence, ( C) and ( D) are correct