When a glass rod is rubbed with a piece of silk cloth

Question

$\begin{array}{1 1} a.\text{ Both cloth and the rod acquire positive charge} \\ b.\text{Rod becomes positively charged while the cloth has a negative charge} \\ c.\text{Rod becomes negatively charged while the cloth has a positive charge} \\ d.\text{Both cloth and the rod acquire negative charge.} \end{array}$