What steps should vegetarians take to ensure they get proper levels of protein

Grains and nuts.

Explanation:

Meat is the main source of protein in ones diet, but people who are vegetarian obviously will need alternative sources of proteins. Good protein options are grains and nuts.

answer: proteins

explanation: complement is   system of circulate in the blood in a inactive form

i believe is what you're looking for?

the correct answer choices are a- b- and d