In moving from A to B along an electric field line, the work done by the electric field on an electron is \[6.4\times {{10}^{-19}}J.\] If \[{{\phi }_{1}}\] and \[{{\phi }_{2}}\]are equipotential surfaces, then the potential difference \[{{V}_{C}}-{{V}_{A}}\] is

• A. -4V      
• B. 4V  
• C. zero      
• D. 6.4V