$S :$ $Sequoia$ $sempervirens$ is an example of an angiosperm.
$R :$ $Eucalyptus$ is the tallest tree in the world.

• 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.