Final answer:
The correct answer is inhalants, substances that are sniffed or inhaled to alter consciousness and create a 'high'. They are distinctly different from stimulants, depressants, or hallucinogens, each of which has unique effects on the brain.
Step-by-step explanation:
The substances whose vapors are sniffed and inhaled to achieve a mind-altering effect are known as inhalants. These are not to be confused with stimulants, which increase alertness and wakefulness, or depressants, which calm the brain and induce sleepiness, or hallucinogens, which can cause profound alterations in perceptions and sensory experiences. Inhalants are used to achieve a quick high by breathing in the chemicals through the nose or mouth, which can lead to various health problems and have serious effects on the nervous system.