Find the sum of the vectors $\overrightarrow a=\hat i − 2\hat j + \hat k, \overrightarrow b=−2\hat i + 4\hat j + 5\hat k$ and $\overrightarrow c = \hat i − 6\hat j – 7\hat k$ .

Question

$\begin{array}{1 1}(A) -4\hat j - \hat k. \\ (B) 4\hat j - \hat k. \\ (C) -4\hat i - \hat k. \\ (D) 4\hat i - \hat k.\end{array} $