$A -$ Calvin cycle starts with the carboxylation of $RuBP$.
$R -$ Photorespiration starts with the oxygenation of $RuBP$.

• A
  $A$ and $R$ are true.
• B
  $A$ and $R$ are false.
• C
  $A$ is true but $R$ is false.
• D
  $A$ is false but $R$ is true.