Final answer:
Chemicals that affect the central nervous system and alter brain activity are psychoactive drugs. They can be legal, prescribed, or illegal and may lead to addiction if misused.
Step-by-step explanation:
Chemicals that affect the central nervous system and alter activity in the brain are known as psychoactive drugs. These include legal substances like caffeine and alcohol, prescription medications such as opioid painkillers, and illegal drugs like LSD and heroin. Psychoactive drugs work by influencing the transmission of nerve impulses, often by acting as agonists or antagonists to neurotransmitters, which can enhance or decrease the activity of these chemical messengers.
Psychoactive drugs can have a variety of effects on mood, thinking, perception, and behavior. Some can be used medically to treat conditions, while others are used recreationally. However, the misuse of psychoactive drugs can lead to addiction, which is characterized by compulsive use despite negative consequences, and may require rehabilitation that includes psychotherapy and potentially other psychoactive drugs.
The correct answer to the schoolwork question is c. Psychoactive drugs.