$S -$ Statement: Cancer is a deadly infectious disease.
$R -$ Reason: $AIDS$ was first reported in the $USA$ in $1986$.

• A
  $S$ and $R$ are both true,$R$ is the correct explanation of $S$.
• B
  $S$ and $R$ are both true,but $R$ is not the correct explanation of $S$.
• C
  $S$ is true and $R$ is false.
• D
  $S$ and $R$ are both false.