$S$: The classification system proposed by $Woese$ is known as the three-domain system.
$R$: $Woese$ divided organisms into three domains: $Archaea$,$Bacteria$,and $Eukarya$.

• A
  $S$ and $R$ are both true,and $R$ 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
  $S$ is false and $R$ is true.