Answer:
The correct answer is answer C: She should use the threat of a mild punishment of he chooses to touch it.
Step-by-step explanation:
Insufficient justification is a psychological phenomenon that happens when an unbalance exists between the threat of a reward/punishment (acting as an external motivator) and a behavior. This reward/punishment has to be mild to have a proper impact on the subject as he/she will generate more intrinsic motivation (motivation generated by ourselfs).
Let's look at this example of the stove.
If the mother uses the threat of a mild punishment the child will think that the action of touching the stove is not that "attractive", so he will lose interest in doing it. He will be intrinsically motivated to not touch the stove.