A)there is a much lower concentration of O₂ in expired air than in atmospheric air.
B)there is a much higher concentration of CO₂ in expired air than in atmospheric air.
C)there is a much higher concentration of O₂ in expired air than in atmospheric air.
D)there is a much lower concentration of CO₂ in expired air than in atmospheric air.
E)the concentrations of CO₂ in expired air and atmospheric air are approximately equal.

A)Rebreathing air from a paper bag
B)Hypoventilation
C)Breath holding
D)Hyperventilation
E)All of these could result in acidosis.

A)external obliques.
B)pectoralis minor.
C)scalenes.
D)external intercostals.
E)All of these are muscles of inspiration.