An amplifier using an opamp with a slew-rate $S R=1$ $V / \mu \mathrm{sec}$ has a gain of $40 \mathrm{~dB}$. If this amplifier has to faithfully amplify sinusoidal signals from dc to $20 \; \mathrm{kHz}$ without introducing any slew-rate induced distortion, then the input signal level must not exceed.
- $795 \; \mathrm{mV}$
- $395 \; \mathrm{mV}$
- $79.5 \; \mathrm{mV}$
- $39.5 \; \mathrm{mV}$