The right option is; b. Their numbers will soon decrease.
When the group of bobcats begins to hunt prey at the base of the mountain and move into the valley below, the numbers of the prey in the valley will soon be reduced. The group of bobcats are known as predators. Predators are animals that hunt and kill other animals (their prey) primarily for food. The activities of predators negatively influence the population of preys in a habitat. When predators hunt and kill other organisms in a habitat, the population of the organisms (prey) will be reduced.