Given below are events occurring during inspiration. Select the correct order of sequence from the options given below.
$(I)$ Air from atmosphere rushes into lungs.
$(II)$ Thoracic volume increases.
$(III)$ Intercostal muscles contract and ribs along with sternum move upward and outward.
$(IV)$ Diaphragm becomes flat and goes downwards.

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