$A-$ In protists and monerans,the parent cell divides into two to give rise to new individuals.
$R-$ Binary fission occurs in Paramoecium.

• A
  $A$ and $R$ are correct,and $R$ is the correct explanation of $A$.
• B
  $A$ and $R$ are correct,but $R$ is not the correct explanation of $A$.
• C
  $A$ is correct,but $R$ is incorrect.
• D
  $A$ is incorrect,but $R$ is correct.