Identify the correct sequence for the mechanism of $HIV$ infection:
$1.$ Viral $RNA$ replicates to form viral $DNA$ with the help of reverse transcriptase.
$2.$ The progeny viruses released in the blood attack other $T_H$ cells and destroy them.
$3.$ Viral $DNA$ gets incorporated into the host cell's $DNA$ and produces virus particles.
$4.$ Virus enters into macrophages.

• A
  $4 \rightarrow 3 \rightarrow 1 \rightarrow 2$
• B
  $2 \rightarrow 1 \rightarrow 3 \rightarrow 4$
• C
  $4 \rightarrow 1 \rightarrow 3 \rightarrow 2$
• D
  $3 \rightarrow 2 \rightarrow 4 \rightarrow 1$