I believe that the answer is C. Hallucinogens but i don't know much about addictions.
Answer:
Mutations
Explanation:
A gene mutation is a permanent change in the DNA sequence of a gene. Mutations can occur in a single base pair or in a large segment of a chromosome and even span multiple genes. Mutations can result from endogenous (occurring during DNA replication) or exogenous (environmental) factors.
It can be a chemical imbalance in the brain, a traumatic event, bad home life, etc.
voluntary movement, perception, homeostasis and cognition (abstract functions)