The mean deviation about median of the numbers $3 x, 6 x, 9 x, \ldots, 81 x$ is 91, then $|x|=$

• A

  4
• B

  $\frac{5}{2}$
• Correct answer
  C

  $\frac{9}{2}$
• D

  8

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