Find a Unit Vector in the Direction of the Given $\mathbf { u } = \langle 0 , - 4 \rangle$

Multiple Choice

Find a unit vector in the direction of the given vector.? $\mathbf { u } = \langle 0 , - 4 \rangle$ ?

A) ? $\langle - 1 , - 1 \rangle$
B) ? $\langle - 1,0 \rangle$
C) ? $\langle 0,0 \rangle$
D) $\langle 0 , - 1 \rangle$
E) ? $\langle 1,0 \rangle$