Final answer:
Ariane's resultant displacement vector points South-West after she drives south and then turns west, as displacement vectors combine directionally.
Step-by-step explanation:
The direction of Ariane's resultant displacement vector after driving south for 7.0 km and then turning west to drive for another 1.4 km is South-West. This is because displacement is a vector quantity, which has both magnitude and direction. Ariane's travel path forms a right-angled triangle with sides of 7.0 km and 1.4 km, representing the south and west components, respectively. The resultant displacement vector lies along the hypotenuse, pointing from the starting point to the final position in a South-West direction.