Answer the following question: Fact 1: Bacteria in soil convert atmospheric nitrogen into a form usable by plants. Fact 2: Plant adds nitrogen to the soil. Given the two facts above, what feeds plants?

Select from the following.
1). animals;
2). insects;
3). virus;
4). bacteria;
5). coal;
6). bees;
7). cells;
8). sugar;
Answer:
4).