Charges are placed on the vertices of a square as shown. Let $\overrightarrow{\mathrm{E}}$ be the electric field and V the potential at the centre. If the charges on A and B are interchanged with those D on D and C respectively, then

 




 

• A

  Both $\overrightarrow{\mathrm{E}}$and V change.

• B

  $\overrightarrow{\mathrm{E}}$and V remain unchanged.

• C

  $\overrightarrow{\mathrm{E}}$changes, V remains unchanged.

• D

  $\overrightarrow{\mathrm{E}}$ remains unchanged, V changes.