ABCD is a square loop having length of side ‘l’ and it is carrying a current i. The loop is placed in a region where a magnetic field $\overrightarrow{\mathrm{B}}=-{\mathrm{B}}_{\mathrm{o}}\left(1+\frac{{\mathrm{x}}^2}{{\mathrm{l}}^2}\right)\widehat{\mathrm{k}}$ exists as shown in figure. Then net force experienced by the loop is

• A

  ${\text{ilB}}_0$

• B

  ${\text{2ilB}}_0$

• C

  ${\text{4ilB}}_0$

• D

  ${\text{3ilB}}_0$