Answer: D. Staying after school is reinforcing for Eric.
Explanation: When an individual is punished for exhibiting a certain behavior or stimulus, exhibiting such stimulus in the future is very likely to decrease. Similarly, when a stimulus is reinforced, the strength to repeat such stimulus in the future increases. In the context above, Keeping Eric after school was perceived by the Ms. Smythe as a punishment and was meant to ensure that he stops swearing, However, since this behavior exhibited by Eric has continued to increase even after being kept after school, then it can be concluded that, Keeping Eric after school is reinforcing this behavior.