Extensive commercial logging, the use of wood for cooking and heating, and excessive clearing of land by subsistence farmers has led to in most areas of sub-saharan africa.
a) erosion
b) deforestation
c) desertification
d) water pollution

It would be B) Deforestation it talks clearly about the use of wood, and clearing the land which include trees.

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