Statement $X$: Boat-shaped body,skin covered with placoid scales.
Statement $Y$: Mouth is generally ventral,jaws are generally toothed.

• A
  Both statement $X$ and statement $Y$ are incorrect.
• B
  Statement $X$ is correct and statement $Y$ is incorrect.
• C
  Both statement $X$ and statement $Y$ are correct. Both are associated with the same class.
• D
  Both statement $X$ and statement $Y$ are correct. Both are not associated with the same class.