Which region dominates the international tourism market as it receives 33% of the 991 million tourist worldwide
a. europe
b. south america
c. asia
d. north america

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.

Don’t use up to much of them it leads to pollution