$\mathrm{A}, \mathrm{B} and \mathrm{C}$ are three concentric metallic shells. Shell $A$ is the innermost and shell $\mathrm{C}$ is the outermost. A is given some charge. Then :

As the charge inside the conducting shell is zero and all the charges are uniformly distributed on the surface of the shells, the charge distributions among the shells is according to figure shown. The inner surfaces of B and C will have the same charge$(-\mathrm{q})$and the outer surfaces of $\mathrm{A}, \mathrm{B} and \mathrm{C}$ will have the same charge $(+\mathrm{q})$. As they have different radius, so they will have different charge density.

Hence the correct answer is 1,3