It can be inferred from the passage that which of...

Câu hỏi: It can be inferred from the passage that which of the following discoverieswas made during the first era in the history of nutrition?

A Protein was recognized as an essential component of diet.

B Vitamins were synthesized from foods.

C Effective techniques of weight loss were determined. 

D Certain foods were found to be harmful to good health.