Yep - you're on to it.
Angiosperms.
California grows sugar beets
Sugar beets can be turned into beet sugar
Canada grows sugar beets
yes
you can store beets about 3 months.
Beets are vegetables, not fruits.
Yes, beets have nitric oxide; but it can only be released when the beets are juiced.
A way that angiosperms are not useful to people as a major source of fertilizer. In angiosperms, after a zygot is formed a fruit forms.
Yes, they are flowering plants/ angiosperms
No - they contain betalins.
The Greek word for "Beets" is "τεύτλα".