If the deer population increases, the consequences in the ecosystem would likely include:
- The lion population would tend to increase due to an abundance of food (deer), assuming other factors also allow for lion population growth.
- The plant population (grass) could decrease as more deer would consume more grass.
Given these considerations, the best responses are:
- The lion population would stay the same. (Incorrect)
- The lion population would decrease. (Incorrect)
- The plant population would increase. (Incorrect)
- The plant population would decrease. (Correct)
So, the most accurate consequence of the deer population increasing is that the plant population would decrease.