$P$: Oleic acid is a long-chain unsaturated fatty acid.
$Q$: In it,two consecutive carbon atoms are joined by a double bond at some positions.

• A
  Both statement $P$ and reason $Q$ are true,and reason $Q$ is the correct explanation of statement $P$.
• B
  Both statement $P$ and reason $Q$ are true,but reason $Q$ is not the correct explanation of statement $P$.
• C
  Statement $P$ is true,but reason $Q$ is false.
• D
  Both statement $P$ and reason $Q$ are false.