I believe it is B i took this test last year.
1. Several places in your digestive system secrete enzymes
2. Enzymes play an important role in every function in the human body
3. Enzymes help with nutrient absorption
If it killed the top level of an ecosystem it would damage the whole ecosystem because it's connected. An organism depends on that top organism which would mean that is that organism dies it would affect the organism that depends on it.