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: Social & Preventive Medicine
In calculating RDA for a particular nutrient, 2 SD are not added for 
Select and explain. 
A. Iron, B. Calcium, C. Energy, D. Vitamin A
C: Energy
Answer: C: Energy 
Explanation: Recommended Dietary Allowance (RDA): Is a level of intake corresponding to Mean + 2 Standard Deviation, which covers requirement of 97.5 % of population

RDA is safe level of intake which is likely to be inadequate in not more than 2.5 % population
RDA 'safe level approach' is NOT USED FOR ENERGY since excess energy intake is undesirable; For energy only mean or average requirement is defined as RDA.