Statement $A$: The number of individuals of each species remains limited due to death.
Reason $R$: Due to death,the materials forming the body of living organisms return to the environment.
Which option is correct for Statement $A$ and Reason $R$?

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