The Value of a That Makes $\mathbf { v } = - \mathbf { i } - \mathbf { j } + \mathbf { k }$

Multiple Choice

The value of a that makes $\mathbf { v } = - \mathbf { i } - \mathbf { j } + \mathbf { k }$ and $\mathbf { w } = 5 \mathbf { i } + a \mathbf { j } + \mathbf { k }$ orthogonal is

A) 6
B) 4
C) -4
D) -2
E) -8