Which of the following is an example of negative reinforcement?

Negative reinforcement involves the removal of an unpleasant stimulus to increase the likelihood of a behavior being repeated. In this case, when someone takes aspirin to relieve a headache, they are removing the discomfort associated with the headache. The relief from pain acts as a reinforcing stimulus that encourages the individual to take aspirin again in the future when experiencing a headache. This demonstrates the principle of negative reinforcement, as the behavior of taking aspirin is strengthened by the removal of an unpleasant experience.

In contrast, the other options do not align with the concept of negative reinforcement. Giving a child a toy for cleaning their room represents positive reinforcement, where a pleasant outcome is added to encourage a behavior. Scolding a student for misbehavior is a form of punishment, which aims to decrease a specific behavior rather than reinforce it. Providing a break after prolonged studying is also not negative reinforcement, as it does not involve the removal of an unpleasant stimulus to encourage a behavior; rather, it is a restorative action that does not fit within the negative reinforcement framework.