Answer:
A. Leukocytes (white blood cells) fight infection, while erythrocytes (red blood cells) transport oxygen.
Explanation:
White blood cells are the doctors of the body. They help your body fight disease and infection. White blood cells produce antibodies that attack and kill pathogens in the body. They are also able to "remember" pathogens, allowing for a faster response if the same pathogen enters the body again.
Red blood cells, on the other hand, are the deliverymen of the body. They contain a protein called hemoglobin that binds to oxygen, allowing them to transport oxygen from your lungs to your other cells. They also transport carbon dioxide waste from your cells back to your lungs.
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