Which of the Following Statements Are True About Negative-Pressure Ventilation

Which of the following statements are true about negative-pressure ventilation (NPV) ?
1) NPV is similar to spontaneous breathing.
2) Airway (mouth) pressure during NPV is zero.
3) Expiration during NPV is by passive recoil.
4) NPV decreases pressure at the body surface.

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