What food source contains all the essential amino acids and is the best source of protein?
Beans
Rice
Meat
Green leafy vegetables

The best source of protein containing all essential amino acids are Meat

Option C

Explanation:

Meat is an animal protein and hence it contains all the essential amino acid in it having nutritional value of more than 45 gms per 100 gms. Other sources have lesser nutritional value for protein such as beans which is said to be a good source of protein but does not have all the essential amino acid and its nutritional value for protein is 15 grams per 100 grams.

Rice is not at all considered to be a good source of protein as its nutritional value for protein is less than 2 gms per 100 grams. Green leafy vegetables are good source but again they are plant protein and do not have all the proteins and essential amino acid though its nutritional value is more than 10 gms but less than 15 gms per 100 gms depending upon variety of vegetables.