Answer: Option D. "Heme"
Explanation:
Deoxyhemoglobin can be defined as a form of which has no oxygen binded to the hemoglobin.
When deoxyhemoglobin is replaced with oxyhemoglobin then the oxygen binds to the heme component of the hemoglobin protein in red blood cells.
Each heme group has iron atom that has the ability to bind to oxygen (02) molecule.
Four oxygen molecules bind to a single hemoglobin protein.
Hence, the correct answer is option D "Heme".