Find the unit vector in the direction of sum of vectors $\overrightarrow{a}=2\hat i+\hat j+\hat k\;and\;\overrightarrow{b}=2\hat j-\hat k$

Question

$\begin{array}{1 1} (A)\;\Large\frac{2\hat i-\hat j-2\hat k }{\sqrt 3} \\ (B)\;\Large\frac{2\hat i+3 \hat j}{\sqrt 3}\\ (C)\;\Large\frac{2\hat i-\hat j-2\hat k }{9} \\ (D)\;\Large\frac{2\hat i-\hat j-2\hat k }{12}\end{array}$