This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
In apoptosis, Apaf-1 is activated by release of which of the following substance from the mitochondria? (NOT RELATED) 
Select and explain. 
A. Bcl-2, B. Bax, C. Bcl-XL, D. Cytochrome C
D: Cytochrome C
Answer: D: Cytochrome C 
Explanation: .