Assuming the $\text{OP-AMP}$ to be ideal. the voltage gain of the amplifier shown below is
- $-\frac{\mathrm{R}_2}{\mathrm{R}_1}$
- $-\frac{\mathrm{R}_3}{\mathrm{R}_1}$
- $-\left(\frac{\mathrm{R}_2 \| \mathrm{R}_3}{\mathrm{R}_1}\right)$
- $-\left(\frac{\mathrm{R}_2+\mathrm{R}_3}{\mathrm{R}_1}\right)$