In given figure, the equivalent capacitance between A and B is

Parallel and series combination of capacitors. 
Three 3$\mathrm{\mu }$F capacitors are in series and their equivalent combination is in parallel to 13$\mathrm{\mu }$F capacitor ${\mathrm{C}}_{\mathrm{net}}=\frac{3}{3}+1=1=2\mathrm{\mu F}$