Proteins are broken down into amino acids. Side note: the enzyme that helps in breaking protein down is called the protease
The correct option is D.
A virus refers to an infectious micro organism that is made up of nucleic acid molecule that is enclosed within a protein coat. Viruses are only able to reproduce and multiply when they come in contact with living cells, in the absence of living cells they remain dormant and they do not show any sign of been a living thing. The nuclei acid molecule of a virus can be in form of a DNA molecule or a RNA molecule.
The affinity of hemoglobin for oxygen is less than its structural analog myoglobin. However, this does not affect hemoglobin's usefulness for the body; on the contrary, it allows hemoglobin to be a more efficient carrier than myoglobin. This is because hemoglobin can release oxygen more easily than can myoglobin. It is both important for oxygen to be carried to different areas and also to be released when needed. The higher affinity of a given protein for oxygen, the harder it will be for that protein to release oxygen when needed. Therefore, hemoglobin's lower affinity for oxygen serves it well because it allows hemoglobin to release oxygen more easily in the body.