In the circuit shown in the figure, there is a switch $S$ which may remain in open or closed position. Equivalent capacitance is calculated between $a \& b$. Which of the following options are correct?

When the switch is open, the equivalent capacitance is 16/3 $\mu F$

When the switch is closed, the equivalent capacitance is 16/3 $\mu F$

When the switch is open, the equivalent capacitance is 8/3 $\mu F$

When the switch is closed, the equivalent capacitance is 8/3 $\mu F$