Final answer:
Once a conditioned response has been extinguished, it will not occur again unless the CS-US pairings are reintroduced. The statement is a) true.
Step-by-step explanation:
The statement is true.
Once a conditioned response has been extinguished, it will not occur again unless the conditioned stimulus (CS) and unconditioned stimulus (US) pairings are reintroduced.
Extinction occurs when the conditioned stimulus is presented repeatedly without being paired with the unconditioned stimulus.
During extinction, the conditioned response gradually weakens and disappears.