This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
Memory cells don't undergo apoptosis due to the presence of which growth factor? 
Select and explain. 
A. Platelet derived growth factor, B. Nerve growth factor, C. Insulin like growth factor, D. Fibroblast growth factor
B: Nerve growth factor
Answer: B: Nerve growth factor 
Explanation: Nerve growth factor was the first identified protein with anti-apoptotic activity on neurons. This prototypic neurotrophic factor, together with the three structurally and functionally related growth factor. Hence nerve cells don&;t undergo apoptosis.