Answer:
Tertiary.
Explanation:
Primary structure of proteins refers to the order of amino acids that make up the protein. The heme is an nonprotein non-amino acid, so it is not involved at this stage.
Tertiary structure of proteins is the overall 3-D folding of the protein (it comes after secondary, which involves folding into a repeated pattern). The heme bonds to its correct position on the hemoglobin during this stage and helps in correct folding.
The answer for this one is b) Looping of DNA
Builds protein is the correct answer
I think the answer you are looking for is peer review.