The vector that must be added to the vectors $\hat{\mathbf{i}}-2\hat{\mathbf{j}}+3\hat{\mathbf{k}}\text{ and }6\hat{\mathbf{i}}+3\hat{\mathbf{j}}-7\hat{\mathbf{k}}$  so that the resultant vector is a unit vector along the Y-axis is

• A

  $4\hat{\mathbf{i}}+2\hat{\mathbf{j}}+5\hat{\mathbf{k}}$

• B

  $-7\hat{\mathbf{i}}+4\hat{\mathbf{k}}$

• C

  $3\hat{\mathbf{i}}+4\hat{\mathbf{j}}+5\hat{\mathbf{k}}$

• D

  null vector