Identify the sequence of steps involved during inspiration in rabbit

Question

(A) Volume of thoracic cavity increases

(B)Contraction of external intercostal muscles moves the rib cage forward

(C) Diaphragm becomes flat

(D) Thoracic cavity expands drawing air into lungs.

$\begin {array} {1 1} (1)\;(C) \rightarrow (B) \rightarrow (A) \rightarrow (D) & \quad (2)\;(C) \rightarrow (A) \rightarrow (B) \rightarrow (D) \\ (3)\;(A) \rightarrow (B) \rightarrow (C) \rightarrow (D) & \quad (4)\;(A) \rightarrow (D) \rightarrow (B) \rightarrow (C) \end {array}$

 

$\begin {array} {1 1} (1)\;(1)\: and \: (2) & \quad (2)\;(1)\: and \: (3) \\ (3)\;(1) \: and \: (4) & \quad (4)\;(3) \: and \: (4) \end {array}$