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
"Foli a deux" is 
Select and explain. 
A. Delusion of doubles, B. Substance abuse disorder, C. Sharing delusion with one more person, D. Dissociation disorder
C: Sharing delusion with one more person
Answer: C: Sharing delusion with one more person 
Explanation: The person with delusion influences the other to develop same delusion.
2 persons sharing same delusion  - "Foli a deux".
3 persons sharing same delusion  - "Foli a trios".
Sharing a delusion to group of people : Pseudo community.