For the compensated attenuator of the given figure, the impulse response under the condition $R_{1} C_{1} = R_{2} C_{2}$ is
- $\frac{R_{2}}{R_{1}+R_{2}}\left[1-e^{-\frac{1}{R_{1} C_{1}}}\right] u(t)$
- $\frac{R_{2}}{R_{1}+R_{2}} \delta(t)$
- $\frac{\mathrm{R}_{2}}{\mathrm{R}_{1}+\mathrm{R}_{2}} u(t)$
- $\frac{\mathrm{R}_{2}}{\mathrm{R}_{1}+\mathrm{R}_{2}} 1-e^{-\frac{1}{R_{1} C_{1}}} \cdot u(t)$