Final answer:
To descend the fastest, you should walk downhill as it aligns with the direction of the gravitational acceleration vector. The correct answer is B.
Step-by-step explanation:
To descend the fastest, you should walk downhill. This is because walking downhill is in the direction of the gravitational force acting on you, which pulls you towards the center of the Earth. Walking uphill would mean working against the force of gravity, hence would not allow you to descend. Walking sideways would lead to a more gradual descent as compared to straight downhill. In the context of physics and vectors, walking downhill can be seen as moving in the direction of the gravitational acceleration vector which is directed towards the center of the Earth.