Rhonda had tartar sauce with her fish one night. The next morning she was nauseated and sick for much of the day. The next time she was offered the chance to go out for fish, she felt queasy and declined. Her queasiness at the thought of fish with tartar sauce was probably due to

a. a conditioned taste aversion.

b. higher-order conditioning.

c. stimulus substitution.

d. stimulus generalization.