$\lim _{n \rightarrow \infty} \frac{1}{n^3} \sum_{k=1}^n k^2 x=$

• A

  x
• B

  $\frac{x}{2}$
• Correct answer
  C

  $\frac{x}{3}$
• D

  $\frac{x}{4}$

Hence, the correct answer is option: 'C'.