Correct answer: B). It would increase
A food chain consists of various level, which starts from producers and ends up to top consumers.
Plants produce the food by the process of photosynthesis. Herbivores such as deer form the first level of consumers as they eat plants. Carnivores like lions consume deer and form the higher level consumers.
If the herbivores population in an ecosystem is increasing, then there would be enough food for carnivores, which would lead to increase in the population of carnivore as there is the huge amount of food available for them.