In the following figure, $\text{C}_1$ and $\text{C}_2$ are ideal capacitors. $\text{C}_1$ has been charged to $12\;\text{V}$ before the ideal switch $\text{S}$ is closed at $t=0$. The current $i(t)$ for all $t$ is
- $\text{zero}$
- $\text{a step function}$
- $\text{an exponentially decaying function}$
- $\text{an impulse function}$