Sarah Has Learned to Ignore Her Parents the First Few

Sarah has learned to ignore her parents the first few times they tell her that it's bedtime. James has learned to respond to his parents the first time they mention bedtime. Both sets of parents punish their children for disobedience, but James parents tend to punish much more quickly than do Sarah's parents. The difference between Sarah's and James' responses to their parents is probably due to __________

A) the temporal relationship between the conditioned stimulus and the unconditioned stimulus.
B) the intensity of the unconditioned stimulus.
C) the number of pairings of the conditioned stimulus and the unconditioned stimulus.
D) the intensity of the conditioned stimulus.