A reinforcer that takes on its reinforcing properties only through association with other reinforcers is called a(n) ________ reinforcer.

A) indirect
B) delayed
C) secondary
D) primary

A secondary reinforcer is a stimulus or event that has acquired reinforcing properties through association with other reinforcers, such as primary reinforcers like food or water. For example, if a rat learns to associate a click sound with a food reward, the click sound may become a secondary reinforcer, acquiring its own reinforcing properties even in the absence of the primary reinforcer (food).