Combination of Capacitors question from JEE Main 2014 (9 Apr, Shift 1)

Answer: (d)

1. All series: $\frac{3}{3} = 1\ \mu\text{F}$; all parallel: $9\ \mu\text{F}$.
2. Two series + one parallel: $1.5 + 3 = 4.5\ \mu\text{F}$.
3. Two parallel + one series: $\frac{6\times3}{6+3} = 2\ \mu\text{F}$.
4. $6\ \mu\text{F}$ is not possible using all three. So the answer is (d) $6\ \mu\text{F}$.