Side effects from using drugs are plentiful, but each group of drugs usually have different effects to the users. Depressants would cause you to move slower and to lose your sense of balance, while stimulants would increase your heartrate and make you more alert. Hallucinogens would cause you to shake a lot and be restless.
Thus, from all the available options, the answer to the blank space given is (C) hallucinogens.
