Oxygen Is Bubbled Through Water Before It Is Given to a Patient

Multiple Choice

Oxygen is bubbled through water before it is given to a patient in a hospital.
What volume of pure oxygen gas at 21.0°C and 750.0 torr pressure would a patient receive if the patient breathed 0.250 L of O₂ bubbled through water at this temperature and pressure? (P_H2O = 19.0 torr at 21°C)

A) 0.00633 L
B) 0.244 L
C) 0.250 L
D) 0.256L
E) none of the above