Answer:
D. To promote changes in farming that temperature increases make necessary
Step-by-step explanation:
According to this excerpt from "A Student's Guide to Global Climate Change.", the author talks about how climate change can affect the growth of crops, as of he climate is too hot, it can scorch the crops and make them difficult to survive and if it rains much, can cause flooding and destroy crops. Therefore, he uses a problem-solution text to show that there are alternatives to make in case of any climate change.
Therefore, the most likely reason the writer uses a problem-solution text structure in this excerpt is to promote changes in farming that temperature increases make necessary