This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc., Subject name: Pathology
IL-2 activates Th 1 /CD 4 through 
Select and explain. 
A. NK cells, B. Th cells, C. T memory cells, D. All the above
D: All the above
Answer: D: All the above 
Explanation: (D) All the above