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: Unknown
Specific marker for GIST is? 
Select and explain. 
A. CD 117, B. CD 34, C. CD 23, D. S-100
A: CD 117
Answer: A: CD 117 
Explanation: Ans. is 'a' i.e., CD 117