For (2n + 1) observations ${\mathrm{x}}_1,-{\mathrm{x}}_1,{\mathrm{x}}_2,-{\mathrm{x}}_2,\dots ,{\mathrm{x}}_{\mathrm{n}},-{\mathrm{x}}_{\mathrm{n}}$, and 0, where all x's are distinct, let SD and MD denote the standard deviation and median, respectively. Then which of the following is always true?

• A

  SD < MD

• B

  SD > MD

• C

  SD = MD

• D

  Nothing can be said in general about the relationship between SD and MD