This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nutrition and health, Subject name: Social & Preventive Medicine
The optimum calories to be provided by proteins should be 
Select and explain. 
A. 5-10%, B. 10-15%, C. 15-20%, D. 20-30%
B: 10-15%
Answer: B: 10-15% 
Explanation: The main source of energy in the diet is carbohydrates derived largely from cereals and provide 50-80% of daily intake. Most families derive 10-12% of energy from proteins. Energy from fats may vary from 5-30%.Ref: Park; 23rd ed; Pg 634