Which Advice Would Assist the Protein Nutrition of Most Vegetarians

Which advice would assist the protein nutrition of most vegetarians?

A) Vegetarians in general must practice complementary protein nutrition.
B) Most vegetarians should consume gelatin to ensure adequate tryptophan intake.
C) Vegan diets in North America rarely meet protein quality needs.
D) Most vegetarians eating a variety of foods need not balance essential amino acid intake at each meal.