As a factor of production, land best refers to a. the ground not covered by waterb. land owned by buisnessesc. all natural resources    d. farming soil only

C.all natural resources  

It is the doctrine that the us had the right and duty to expand throughout north america. it just means they believed they had the right to expand westward and they did! they stated with the 13 colonies and then they kept moving gaining different territories throughout the years