State the sequence of events for inspiration (breathing in).
$I$ - Increase in lung volume
$II$ - Decrease in intrapulmonary pressure
$III$ - Contraction of respiratory muscles
$IV$ - Increase in thoracic volume
$V$ - Air rushes into the lungs

• A
  $V \rightarrow IV \rightarrow I \rightarrow II \rightarrow III$
• B
  $V \rightarrow IV \rightarrow I \rightarrow III \rightarrow II$
• C
  $III \rightarrow V \rightarrow I \rightarrow IV \rightarrow II$
• D
  $III \rightarrow IV \rightarrow I \rightarrow II \rightarrow V$