A conducting rod AC of length 4l is rotated about a point O in a uniform magnetic field $\overrightarrow{\mathrm{B}}$ directed into the paper. AO = l and OC = 3l. Then 

• A

  ${\mathrm{V}}_{\mathrm{A}}-{\mathrm{V}}_{\mathrm{O}}=\frac{{\mathrm{B\omega l}}^2}{2}$

• B

  ${\mathrm{V}}_{\mathrm{O}}-{\mathrm{V}}_{\mathrm{C}}=\frac{7}{2}{\mathrm{B\omega l}}^2$

• C

  ${\mathrm{V}}_{\mathrm{A}}-{\mathrm{V}}_{\mathrm{C}}=4{\mathrm{B\omega l}}^2$

• D

  ${\text{V}}_{\mathrm{C}}-{\mathrm{V}}_{\mathrm{O}}=\frac{9}{2}{\mathrm{B\omega l}}^2$