Are these destructive methods always natural?

The greenhouse effect a. something that has occurred for millions of years b. an unnatural phenomenon caused by humans that maintains earths temperature range. c. the results of the differences in the angle of the suns rays d. an unnatural phenomenon that causes heat energy to be radiated back into the atmosphere

What type of graph presents information about how often certain or traits occur?

In the sentence "a mining company will consider the distribution of coal when deciding how to mine the coal," what does the word distribution mean?