Alaska is the biggest in terms of sq miles
3
Green manure.
Farmyard manure.
Compost manure.
I know jobs for one, over population maybe, and because they are worried that dangerous people could be entering into the country with intention to harm. (unless this is a "only 3 right answer" kind of thing)
It's about the study of the earth. Like mapping, or just looking at different biomes or landscapes.
B. 1 in 4 which is also 25%