$Statement \; 1$: Zero population growth should be achieved as early as possible to control human population.
$Statement \; 2$: This requires not two children per couple but a little more effort on reduction of this number.

• A
  $Statement \; 1$ is True,$Statement \; 2$ is True; $Statement \; 2$ is the correct explanation for $Statement \; 1$.
• B
  $Statement \; 1$ is True,$Statement \; 2$ is True; $Statement \; 2$ is not the correct explanation for $Statement \; 1$.
• C
  $Statement \; 1$ is True,$Statement \; 2$ is False.
• D
  $Statement \; 1$ is False,$Statement \; 2$ is True.