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
Loosening of association is an example of: 
Select and explain. 
A. Formal thought disorder, B. Schneider's first symptoms, C. Perseveration, D. Concrete thinking
A: Formal thought disorder
Answer: A: Formal thought disorder 
Explanation: A. i.e. Formal thought disorder