If the resultant of the vector $(\hat{i}+2\hat{j}-\hat{k}), (\hat{i}-\hat{j}+2\hat{k}) and \overrightarrow{C}$ is unit vector along the y direction t, tan 
$\overrightarrow{C}$ is:
A)  - $2\hat{i}$- $\hat{k}$                 B)    - $2\hat{i}$ + $\hat{k}$             C)   $2\hat{i}$ - $\hat{k}$        D) $2\hat{i}$ + $\hat{k}$