The correct option is B Reduction reaction
In Chemistry, reduction is referred to as the loss of oxygen when it is with respect to the oxygen transfer. It is the job of the reducing agent to remove the oxygen from another substance.
Similarly, in the case of hydrogen transfer, it is the gain of hydrogen. That means it is reducing agent’s work to remove oxygen from one substance and add hydrogen to it.
Alkyl nitriles are reduced using a metal like palladium, platinum or nickel as a catalyst. This is known as catalytic hydrogenation.