The answer is surfacant. Its a fluid secreted by the cells of the alveoli( the tiny air sacs in the lungs) that serves to reduce the surface tension of pulmonary fluid. Surfacant also contributes to the elastic properties of pulmonary tissue , preventing the alveoli from collapsing.
Yes it's a protein called Hemoglobin in the red blood cells and it carries oxygen around your body and to your lungs, so it is TRUE.
Hope this helps! God bess
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