Task: Question Answering
Input (English): Question: To measure the pulmonary wedge pressure (PEP) by means of a pulmonary artery catheter, it is advisable to take into account that: 
 Options:  <1> It is not necessary to inflate the ball. <2> The catheter should always be inserted with the balloon inflated, but at half the recommended volume. <3> The volume of balloon inflation is usually 1.5 ml of air. <4> The volume of inflation of the balloon is usually 3 ml of air. <5> You have to leave the balloon always inflated after making the determinations of PEP.
Output (English): 3