Which resource is rich in the caucasus region?
a. lumber
b. silver
c. copper
d. oil?

The caucasus region is rich in oil. Oil was discovered in the Caucasus region as early as the 13th century. Technological advancement made it possible to access these rich oil reserves. Through trade of oil, the Caucasus region rose to prominence and exerted its dominance over most of Asia. 

Geothermic gradient is the rate of increasing temperature with respect to increasing the depth in the earths interior. away from tech tonic plates boundaries, it is about 25-40 c/km (72-87 degrees f/mi) of depth near the surface in most of the world.

Answerair masses develop near the equator are warm; tropical air mass