Answer:
The main idea of this paragraph is that red blood cells are specialized cells. So Option C is the correct one.
Step-by-step explanation:
Red blood cells are disk-shaped which can move through very small veins and arteries. It contains a protein molecule - Haemoglobin that helps to transport both oxygen to your cells and take away carbon dioxide and waste away from the cells as well. Having a normal level of these cells is important.
Lesser levels mean anaemia and other complications. A higher level may also be a sign of a health problem so having a normal level of RBCs is necessary. Since, they perform some very important functions that’s why they can be called specialized cells.