Statement $P$: The quaternary structure of proteins is either globular or fibrous.
Statement $Q$: The three-dimensional arrangement of molecules consisting of a single polypeptide chain is the quaternary structure of proteins.

• A
  Statement $P$ is true,Statement $Q$ is false.
• B
  Statement $P$ is false,Statement $Q$ is true.
• C
  Both Statement $P$ and $Q$ are false.
• D
  Both Statement $P$ and $Q$ are true.