Final answer:
To come to an abrupt halt at the bottom of a hill, a skier should apply the brakes, either through a snowplow or parallel stop, to safely reduce speed and stop.
Step-by-step explanation:
If a skier has reached the bottom of a hill and is making plans to come to an abrupt halt, the action the skier should take is d) Apply the brakes. This is the most efficient and controlled method for stopping, as it is directly designed to counteract the skier's momentum. In skiing terminology, 'applying the brakes' usually means engaging in a snowplow stop or a parallel stop. Both techniques involve turning the skis inward and pressing down, causing friction and thus slowing the skier down gradually until they come to a complete stop.
The snowplow stop is preferable for beginners, as it's easier to balance, while the parallel stop is commonly used by more experienced skiers for a faster and more abrupt halt. It is important to note that performing a sharp turn or a jump when trying to stop could increase the risk of losing control or causing an injury.