Answer
(e) $\frac { 3}{2} C$
Work Step by Step
let $C_1$ be the equivalent capacitance of the two capacitors in series
$\frac{!}{C_1} = \frac{1}{C} + \frac{1}{C}$
$C_1 = \frac {1}{2} C$
now equivalent capacitance of the whole combination
$C_{eq} = C_1 + C = \frac{1}{2} C +C $
$C_{eq} = \frac { 3}{2} C$
