Each of Two Vectors, and , Lies Along

Multiple Choice

Each of two vectors, and , lies along a coordinate axis in the xy plane. Each vector has its tail at the origin, and the dot product of the two vectors is . Which possibility is correct?

A)
and
both lie along the positive x axis.
B)
lies along the positive x axis.
lies along the negative x axis.
C)
and
both lie along the positive y axis.
D)
lies along the negative x axis.
lies along the negative y axis.
E)
lies along the positive y axis.
lies along the negative x axis.