$\text{ For }(2n+1)\text{ observations }{x}_1,-x_1,x_2,-x_2,\dots ,x_n,-x_n\text{ and }0\text{ , }$

$\mathrm{where}\mathrm{all} x\text{ 's are distinct, let }\mathrm{SD}\text{ and }\mathrm{MD}\text{ denote the standard deviation}$

$\text{and median respectively. Then which of the following is always true? }$

• A

   SD < MD 

• B

   SD > MD 

• C

  SD = MD 

• D

  None of these