Six-year-old Jack has recently learned to appreciate the value of money, so his father assigns him some simple housekeeping chores to be performed throughout the week. He tells Jack that completion of these chores will earn him an allowance of one dollar every Saturday. Jack rarely completes his chores.

From a behaviorist perspective, which one of the following is most likely to be the reason why Jack is not doing his chores?

a. Reinforcement is not immediate.

b. Reinforcement is not contingent on the desired response.

c. Money is not an effective reinforcer for most six-year-olds.

d. The reinforcer is presented before the response