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: Physiology
Which of the following growth factor maintain the neurons by reducing apoptosis therefore the memory cells does not undergo apoptosis? 
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: The first neurotrophin to be characterized was nerve growth factor (NGF), a protein growth factor that is necessary for the growth and maintenance of sympathetic neurons and some sensory neurons. NGF is picked up by neurons and is transpoed in retrograde fashion from the endings of the neurons to their cell bodies. It is also present in the brain and appears to be responsible for the growth and maintenance of cholinergic neurons in the basal forebrain and the striatum. There is evidence that the maintenance of neurons by NGF is due to a reduction in apoptosis. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 4. Excitable Tissue: Nerve. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong's Review of Medical Physiology, 24e.