During electrolysis the reaction at anode is? 

Electrolysis is the chemical process of using an electrical current to stimulate nonspontaneous reactions. A non-spontaneous reaction is one that needs energy to work while it proceeds. In other words, the process would not happen on its own, as it goes in an unfavorable, or a reversed, direction. This process requires an anode, a positively charged electrode, and a cathode, a negatively charged electrode. Oxidation occurs at anode and reduction occurs at the cathode. Hence, option A is correct.