This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nutrition, Subject name: Medicine
Calorie restriction increases longevity through - 
Select and explain. 
A. Siruins, B. Albumin, C. Amyloid, D. Carotene
A: Siruins
Answer: A: Siruins 
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 Harrison 20th edition pg 78