Whenever tommy has a babysitter and asks to stay up past his bedtime, the babysitter lets him. whenever tommy asks his parents to let him stay up past his bedtime, they do not let him. as a result, tommy only asks the babysitter if he can stay up past his bedtime. the presence of the babysitter at bed time is referred to as a(an) for asking to stay up late.
a. stimulus class
b. s-delta
c. reinforcer
d. discriminatve stimulus

d) Discriminative Stimulus

Explanation:

Discriminative stimulus is defined as term in classical conditioning in which the stimulus is utilized for obtaining a particular feedback from someone.It helps in getting the responses that are desired by an individual and increase those response accordingly.

According to the situation it also describes discriminative stimulus as Tommy prefers to ask about staying up past the bedtime from babysitter as he gets the desired response in the form of permission to stay up. His parent did not let him stay up late so the feedback was not favorable to Tommy's desire.

Other options are incorrect because stimulus class have same element consisting cluster of stimulus. S-delta is the stimulus in which non-enforced behavior is present. Reinforcer is stimulus that encourage for gaining particular response.

Thus, the correct option is option(d).