A metallic sheet, in the form of a square ABCD, has non-uniform distribution of mass. Two forces 10 N and 20 N are applied on the sheet as shown in figure. It is observed that the sheet makes only translational motion. Then distance of centre of mass from the corner A may be 

• A

  $\sqrt{11}\mathrm{cm}$

• B

  $5 \mathrm{cm}$

• C

  $6 \mathrm{cm}$

• D

  $\sqrt{17}\mathrm{cm}$