Vector of magnitude $3$ making equal angles with $x$ and $y$ axes and perpendicular to $z$ axis is (A) $\hat{i} + 2\sqrt{2} \hat{j}$ (B) $3\hat{k}$ (C) $\frac{3\sqrt{2}}{2} \hat{i} + \frac{3\sqrt{2}}{2} \hat{j}$ (D) $\sqrt{3} \hat{i} + \sqrt{3} \hat{j} + \sqrt{3} \hat{k}$