The drain of an $n$-channel MOSFET is shorted to the gate so that $V_{G S}=V_{D s}$. The threshold voltage $\left(V_{T}\right)$ of MOSFET is $1 \mathrm{~V}$. If the drain current $\left(\mathrm{I}_{\mathrm{D}}\right)$ is $1 \mathrm{~mA}$ for $\mathrm{V}_{G S}=2 \mathrm{~V}$, then for $\mathrm{V}_{G \mathrm{~s}}=3 \mathrm{~V}, \mathrm{I}_{\mathrm{D}}$ is
- $2 \mathrm{~mA}$
- $3 \mathrm{~mA}$
- $9 \mathrm{~mA}$
- $4 \mathrm{~mA}$