Final answer:
High quality proteins get their label 'high quality' because they have a good ratio of all nine essential amino acids.
Step-by-step explanation:
The label 'high quality' for proteins is attributed to their good ratio of all nine essential amino acids. Complete proteins, which contain adequate amounts of all nine essential amino acids, are considered high quality proteins. Examples of complete proteins include animal proteins like meat, fish, milk, and eggs. On the other hand, incomplete proteins do not provide enough of one or more essential amino acids.