This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Physiology
Siuins are associated with 
Select and explain. 
A. Memory, B. Vision, C. Metabolism, D. Olfaction
C: Metabolism
Answer: C: Metabolism 
Explanation: Siuins are a family of proteins that play a role in aging by regulating cellular health. They're responsible for critical biological functions like DNA expression and aspects of aging. However, siuins can only function in the presence of NAD+, nicotinamide adenine dinucleotide, a coenzyme found in all living cells Ref: guyton and hall textbook of medical physiology 12 edition page number:534,535,536