Which of the following is not a natural cause of climatic change?
a. solar activity
b. human activity
c. volcanic activity
d. earth's tilt
any ?

I think the correct answer from the choices listed above is option B. It is human activity that is not a natural cause of climatic change. Human activity do not happen as it should be. It depends on us how we do things and how much we think how it affects the environment.

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.

Answer any resource, such as wood or solar energy, that can or will be replenished naturally in the course of time;