Niger and Congo are two rivers after which countries are named (actually in both cases two countries each) - and those are African countries, so they must be in Africa.
Zambezi is a river in Angola and Namibia.
Tigris is a River in Mesopotamia, in Asia - so that's the correct answer!
Physical, such as mountains rivers lakes, etc. and/ or political maps of reigons are divided by boundaries.
Answer:
pressure increases as you move deeper below earth's surface
temperature increases as you move deeper below earth's surface
