Answer:c. a secondary reinforcer
Step-by-step explanation:
Secondary Reinforcement a behaviour is reinforced by a stimulus which is related to a previous primary reinforcer or stimulus that is based on our survival instinct.
Secondary reinforcer is meant to either assist us or do the opposite of that such as clicking for a chicken at first the chicken hears this and see that you doing it to give them food now when they hear clicking they associate it with food so clicking becomes a secondary reinforcer associated with primary reinforcer.
Clicking doesn't directly fulfill your hunger but it's a means to get the food hence it's secondary reinforcer.