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Consider the circuit with an ideal $\text{OPAMP}$ shown in the figure.

Assuming $\left | V_{\text{IN}} \right |\ll \left | V_{\text{CC}} \right |$ and $\left | V_{\text{REF}} \right |\ll \left | V_{\text{CC}} \right |$, the condition at which $V_{\text{OUT}}$ equals to zero is

1. $V_{\text{IN}}\:=\:V_{\text{REF}}$
2. $V_{\text{IN}}\:=\:0.5\:V_{\text{REF}}$
3. $V_{\text{IN}}\:=\:2\:V_{\text{REF}}$
4. $V_{\text{IN}}\:=\:2\:+\:V_{\text{REF}}$