Answer:
The answer is B. biochemical.
Step-by-step explanation:
Many studies have shown the biochemical effects of drugs (i.e. effects related to hormones and enzymes released by the brain when using the substances).
Drugs can alter the way neurons communicate with each other; they might activate or inhibit them, and this may interfere with the normal functioning of the brain. An excess of neurotransmitters (as produced by cocaine, for example) could interfere with the regular life cycle of neurons and disrupt the behaviour of neurons.