The Value of a That Makes $\mathbf { v } = 2 \mathbf { i } - \mathbf { j } + 3 \mathbf { k }$

Multiple Choice

The value of a that makes $\mathbf { v } = 2 \mathbf { i } - \mathbf { j } + 3 \mathbf { k }$ and $\mathbf { w } = 4 \mathbf { i } + a \mathbf { j } + \mathbf { k }$ orthogonal is

A) 7
B) 11
C) 13
D) -11
E) -7