Every friday, dr. cruz would give a quiz in his psychology class. students quickly learned to be nervous on friday mornings, just before each quiz. halfway through the semester, dr. cruz stopped giving quizzes on fridays and the students' anxiety began to diminish with each passing week in which there was no quiz. the decrease in the students' anxiety may be attributed to the process of:
a. spontaneous recovery.
b. extinction.
c. stimulus generalization.
d. latent learning.