a
\(C\,\, = \,\,\frac{{{\varepsilon _0}A}}{d}\,\, \Rightarrow \,\,A\,\, = \,\,\frac{{CD}}{{{\varepsilon _0}}}\,\, = \,\,\frac{{3\,\, \times \,\,5\,\, \times \,\,{{10}^{ - 3}}}}{{8.85\,\, \times \,\,{{10}^{ - 12}}}}\,\, = \,\,1.694 \times {10^9}\,{m^2}\)