What type of drug includes common examples such as amphetamines and cocaine?

The correct choice is stimulants because this category of drugs is characterized by their ability to increase activity in the central nervous system, leading to enhanced alertness, attention, and energy. Common examples of stimulants include amphetamines and cocaine, both of which are known for their stimulating effects on the brain that can result in increased heart rate, increased blood pressure, and a feeling of euphoria.

In contrast, narcotics are primarily pain-relieving medications that can lead to sedation and are derived from opiates. Depressants are substances that reduce brain activity and can lead to relaxation or drowsiness, while hallucinogens alter perception, mood, and various cognitive processes. Each of the other categories serves different physiological and psychological functions, setting them apart from stimulants and their associated effects.