Identify $X$ and $Y$ in the given diagram of a nucleosome.

• A
  $X = \text{DNA}$, $Y = H_1$ histone
• B
  $X = \text{Histone octamer}$, $Y = \text{DNA}$
• C
  $X = \text{DNA}$, $Y = \text{Histone octamer}$
• D
  $X = H_1$ histone, $Y = \text{DNA}$