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: Medicine
B cell functions is tested by all of the following except ? 
Select and explain. 
A. C H 50 count, B. Amount of Ig G, C. PPD testing, D. Cytokine
A: C H 50 count
Answer: A: C H 50 count 
Explanation: None