Answer:
D. 5.8 cm, 31 degrees South of the West axis
Step-by-step explanation:
Here we have two vectors:
direction west
direction south
We note that the two vectors are perpendicular, so we can use the Pythagorean's theorem to find the magnitude of their resultant:

The direction can be found as follows:

And according to how we calculated the ratio inside the formula, this angle is measured as south of west.