This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Symptoms and signs in psychiatry and classification, Subject name: Psychiatry
Serial subtraction is used to test 
Select and explain. 
A. Working memory, B. Long term memory, C. Mathematical ability, D. Recall power
A: Working memory
Answer: A: Working memory 
Explanation: Working memory- Digit Span test & serial subtraction.Long term memory- bih, high school, marriage details, etc. DST & Serial subtraction are usually tested for concentration., here correct option is working memory. Reference: Syanopsis of Psychiatry, page 203.