c
\({C_{1\,}}\, = \,\,\frac{{{ \in _0}\,A}}{d}\)

\(\,\frac{1}{{{C_2}}}\,\, = \,\,\frac{1}{{2\,{ \in _r}\,{C_1}}}\,\, + \;\,\frac{1}{{2{C_1}}}\)

\({C_2}\,\, = \,\,\frac{{2\,{ \in _r}\,{C_1}\, \times \,\,2{C_1}}}{{2\,\,{ \in _r}\,{C_1}\,\, + \;\,2{C_1}}}\,\,\,\,\,\therefore \,\,\,\,{C_2}\,\, = \,\,\frac{{4\,{ \in _r}\,{C_1}}}{{2{C_1}\,\,\left( {1\,\, + \,\,{ \in _r}} \right)}}\,\,\, \Rightarrow \,\,{C_2}\,\, = \,\,\frac{{2\,{ \in _r}\,{C_1}}}{{1\,\, + \;\,{ \in _r}}}\)

\({C_{3\,}}\, = \,\,\frac{{2\,\, \times \,\,\infty {C_1}}}{{1\,\, + \,\,\infty }}\,\, = \,\,\infty \)

\(\therefore \,\,\,{C_3}\,\, > \,\,{C_2}\,\, > \,\,{C_1}\)