This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
Jet black pigmentation of tongue with tactile hallucination is a feature of which substance use 
Select and explain. 
A. Heroin, B. Cannabis, C. Cocaine, D. LSD
C: Cocaine
Answer: C: Cocaine 
Explanation: Chronic cannabis use can lead to jet black pigmentation of tongue. And patients may also have feeling of insects crawling under the skin also known as magnan phenomenon.