Task: Question Answering
Input (English): Question: When administering oxygen therapy to a patient admitted to the emergency room due to exacerbated COPD, you should take into account that: 
 Options:  <1> The flow of oxygen must be high, since respiratory failure is accompanied by hypoxia. <2> The concentration of oxygen is conditioned by the patient's clinical situation. <3> The concentration of oxygen must be equal to the atmospheric concentration, since the patient presents hypercapnia. <4> The flow should be low, since hypoxia is the only stimulus to breathe. <5> The flow must be adjusted to achieve a PO2 greater than 90 mmHg.
Output (English): 4