Which of the Following Statements Are True About Low-Flow O₂

Which of the following statements are true about low-flow O₂ delivery systems?
1) The greater the patient's inspiratory flow, the greater is the FiO₂.
2) All low-flow devices provide variable O₂ concentrations.
3) The O₂ provided by a low-flow device is diluted with air.
4) The patient's flow usually exceeds that from a low-flow device.

A) 1 and 3 only
B) 1, 2, and 3 only
C) 3 and 4 only
D) 2, 3, and 4 only