Task: Question Answering
Input (English): Question: Point out the correct statement: 
 Options:  <1> At low pO2, myoglobin is more saturated with O2 than hemoglobin. <2> CO2 increases the affinity of hemoglobin for O2. <3> 2,3 Bisphosphoglycerate is strongly bound in oxygenated hemoglobin. <4> The tissues that produce lactate release more O 2. <5> At high pO2, hemoglobin has 2 subunits.
Output (English): 1