The diagram shows a cross-section of the human cochlea. Which one of the following options correctly identifies the three parts labeled $A$,$B$,and $C$?

• A
  $B$ - Tectorial membrane,$C$ - Perilymph,$D$ - Hair cells.
• B
  $C$ - Endolymph,$D$ - Hair cells,$A$ - Serum.
• C
  $D$ - Hair cells,$A$ - Endolymph,$B$ - Tectorial membrane.
• D
  $A$ - Perilymph,$B$ - Tectorial membrane,$C$ - Endolymph.