Fact 1: Immunodeficiency occurs when the immune system is not working properly. Fact 2: Work items are broken down by year of effort. Given the two facts above, immunodeficiency occurs when the immune system is what?

pick from the following.
1). dangerous
2). homogenous
3). healthy
4). broken down
5). reduce
6). perfect
7). It decreases
8). functioning
Answer:
4).