Linear operators and matrices

Consider a linear operator $\mathcal{A}$ that rotates each vector of the plane around the origin by the angle $\dfrac{\pi}{6}$ (counter clockwise). What is the matrix of this operator?

1) $\begin{pmatrix} \dfrac{\sqrt{3}}{2} & \dfrac{1}{2} \\ \ & \ \\ -\dfrac{1}{2} & \dfrac{\sqrt{3}}{2} \end{pmatrix};$

2) $\begin{pmatrix} \dfrac{\sqrt{3}}{2} & - \dfrac{1}{2} \\ \ & \ \\ \dfrac{1}{2} & \dfrac{\sqrt{3}}{2} \end{pmatrix};$

3) $\begin{pmatrix} \dfrac{1}{2} & - \dfrac{\sqrt{3}}{2} \\ \ & \ \\ \dfrac{\sqrt{3}}{2} & \dfrac{1}{2} \end{pmatrix};$

4) This is not a linear operator.