Derive an expression for the equivalent capacitance of the parallel combination 

Question

$\begin{array}{1 1} (a)\; \large\frac{1}{c}=\frac{1}{c_1}+\frac{1}{c_2} \\ (b)\;C=c_1+c_2\\ (c) C=\large\frac{1}{c_1}+\frac{1}{c_2}\\ (d) C=\large\frac{1}{c_1+c_2}\end{array} $