9. Based on the plot of oxygen saturation versus partial pressure of oxygen, which of the following statenents is true? (A) at oxygen pressure > 100 mm Hg, hemogiobin dissociates into individual subunits so that it is able to bind oxygen similar to myoglobin (B) at typical resting capillary oxygen pressure of ~30 mm Hg, hemoglobin has only 1 of its 4 oxygen binding sites filled while myoglobin is nearly saturated with oxygen (C)under periods of extreme muscle exertion, capillary oxygen pressure can drop to 10 mm Hg, allowing release of ~90% of oxygen carried by hemoglobin (D) the structure of hemoglobin allows for complete release of oxygen in capillary beds at all times (E) none of the above