When an ebonite rod is rubbed with the skin of a cat, the ebonite rod becomes negatively charged (option A). This phenomenon occurs due to the transfer of electrons. Ebonite, being a material that has a strong affinity for electrons, attracts and gains electrons from the cat’s skin during the rubbing process. As a result, the ebonite rod accumulates an excess of negatively charged electrons, which leads to it becoming negatively charged. The cat’s skin, having lost some of its electrons, becomes positively charged in turn. This transfer of electrons is a classic example of triboelectric charging, where contact and friction between two different materials result in one material gaining electrons and the other losing them. Therefore, the ebonite rod acquires a negative charge after rubbing with the cat’s skin.