Why not B?
I know there are four premises:
1. Cattle feed --> destroy North America prairie;
2. the prairie once supported 30-70M Bison, now supports about 50M cattle (what's the purpose of this premise? doesn't this mean that returning the land to bisons will be more cost efficiently than raising cattle?)
3. Bison yield as much meat as cattle;
4. natural prairie: no requirement for pesticides, machinery, and etc.
Conclusion: if we return as much land as possible to an uncultivated state, we could restore biodiversity without a major decrease in meat production.
I know E is good, but I thought it is just a reiterate of the main conclusion in the stimulus. So I chose B.
Thanks in advance for your help!