Select the correct answer regarding the transport of oxygen in the blood?

1) during normal activity, a hemoglobin molecule returned to the lungs contains a molecule of O2 2) under conditions of acidosis, hemoglobin can transport oxygen more efficiently 3) increased levels BPG in red blood cells that carries oxygen to enhance the capabilities of 4) 50% the level of oxygen saturation of blood to the lungs of the survey may indicate an activity level higher than normal

1 is correct.

obstructive sleep apnoea 80 seconds 51% oxygen saturation