Rivers provided food and fresh water, as well as fertile soil that would be suitable for growing basic crops.
Answer:
Option: (D) To identify patterns of diffusion and their effect on the host country.
Explanation:
The geographer purpose of studying the pattern of migration is to look at the reasons for the people leaving their native country and migrating to the host country.
To check the migrant's effects on the host country, it would be useful to divide two groups according to their skills - highly educated and skilled labor. Migration would affect the country because they will help the host country to built-in a good shape by their skills and knowledge.
D. A place where some magma reaches Earth's surface.
The correct answer would be c because in the picture above it shows two oceanic plates colliding.