The capacitance of a concentric spherical capacitor of shell radii x and y (x > y) is

• A. \(\frac{1}{{4\pi {\varepsilon _0}}}\ln \frac{x}{y}\)
• B. \(\frac{{4\pi {\varepsilon _0}xy}}{{x - y}}\)
• C. \(4\pi {\varepsilon _0}\ln \frac{y}{x}\)
• D. \(\frac{1}{{4\pi {\varepsilon _0}}}\left[ {\frac{1}{y} - \frac{1}{x}} \right]\)