A day care program frequently has a few parents picking up their children late. In an attempt to curb this, the daycare decides to charge a fine to parents who are more than 10 minutes late. However, after the fine was implemented, the number of late parents increased. Which of these conclusions can be true?

a. The fine eliminated the non-financial incentives to be on time
b. The fine was not high enough to discourage being late
c. The fine was perceived as a price
d. All of the above