A Patient with a Tracheal Airway Exhibits Signs of Tube

A patient with a tracheal airway exhibits signs of tube obstruction. Which of the following are possible causes of this obstruction?
1) The tube cuff has herniated over the tip of the tube.
2) The tube is obstructed by a mucus plug or secretions.
3) The tube is kinked, or the patient is biting the tube.
4) The tube orifice is impinging on the tracheal wall.

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