A type of learning in which behavior is strengthened if followed by a reinforcer is called

A) delayed conditioning.
B) classical conditioning.
C) primary conditioning.
D) operant conditioning.

Operant conditioning involves learning through consequences, where behavior is strengthened by positive reinforcement (receiving a reward) or negative reinforcement (removal of an aversive stimulus). This is different from classical conditioning, which involves learning by association between two stimuli. Delayed conditioning is not a recognized type of learning, and primary conditioning is not a commonly used term in psychology.