## **Core Concept**
The Recommended Dietary Allowance (RDA) of protein is the average daily intake level sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy individuals in a particular life stage and gender group. Protein is essential for growth, maintenance, and repair of body tissues.

## **Why the Correct Answer is Right**
The RDA for protein in adult men is set at 0.8 grams per kilogram of body weight per day. This translates to approximately 56 grams of protein per day for a 154-pound (70 kg) man. This value is based on the essential amino acid requirements and the average body size of adults in the United States.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it does not accurately reflect the RDA for protein in adult males.
- **Option B:** This option is incorrect because, similar to option A, it does not match the established RDA for protein.
- **Option D:** This option suggests a higher value than the established RDA for adult males, which might be recommended for specific conditions or active individuals but not for the general adult male population.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that while the RDA for protein in adult males is 0.8 grams/kg/day, individual protein needs can vary based on activity level, age, and health status. For example, athletes or those with certain medical conditions may require more protein.

## **Correct Answer:** . 56 g/day