Question

what do white blood cells do? play a key role in in transporting hemoglobin. play a key role in in transporting carbon dioxide. play a key role in fighting off infections. play a key role in in transporting glucose. play a key role in fighting off blood clotting.

Explanation:

White blood cells, or leukocytes, are part of the immune system. Their main function is to defend the body against infections. Red blood cells transport hemoglobin (which carries oxygen) and also help with carbon dioxide transport. Platelets are involved in blood clotting. Glucose is transported in the blood plasma.

Answer:

Play a key role in fighting off infections.