A sphere of radius 2R has a uniform charge density \[\rho .\] The difference in the electric potential at \[r=R\], \[r=0\]from the center is

• A. \[\frac{-\rho {{R}^{2}}}{{{\in }_{0}}}\]
• B. \[\frac{-2\rho {{R}^{2}}}{{{\in }_{0}}}\]
• C. \[\frac{\rho {{R}^{2}}}{3{{\in }_{0}}}\]
• D. \[\frac{-\rho {{R}^{2}}}{6{{\in }_{0}}}\,\]