I believe it is the crust
Adrenaline
Nicotine is a substance that is addictive in nature commonly
found in cigarette, that affect the nervous system by binding to the receptors
in the brain and other part of the body. Atherosclerosis is the loss of
elasticity or thickens of arteries walls. However, nicotine increases the
release of neurotransmitter adrenaline into the blood which subsequently cause
the development of atherosclerosis.
First, we can eliminate 2 options. The simple unit of protein is amino acid, instead, the simple unit of fat and lipids are fatty acids and glycerol, therfore we can eliminate option A and D because fatty acids does not exist in protein.
Now we are left with B and C. To solve that, we need to understand that protein is made of a chain of amino acids, a lot of amino acids are chemically combined and cannot be broken down unless the use of enzymes. Amino acid are actually the monomers that forms protein.
Therefore, the answer is C. amino acid combine to form a protein chain.
Carbon can form single, double, and triple bonds with other carbon atoms.