A very intense summer region with little rainfall causes a decrease in the amount of water for the animals. This is because intense summer evaporates much of the water available to animals, as in this region, rain is scarce, evaporated water takes time to return to the ground, which can cause a severe drought that makes water a limiting factor for animal life.
Therefore, we can conclude that the correct answer to your question is the letter D.
The mutations occur at a rate of 0.56 base changes every 1 billion years. If this rate stays consistent, the mutation rate can be used to determine when different lineages of a particular species split
