Which statement best illustrates the MAOA gene-environment interaction in aggression?

• A. Low-activity MAOA variants increase aggression risk regardless of environment.
• B. Low-activity MAOA variants increase aggression risk only when paired with childhood maltreatment.
• C. High-activity MAOA variant interacting with maltreatment markedly increases aggression risk.
• D. There is no gene-environment interaction for MAOA and aggression.

Answer: (B)