Hi, you've asked an incomplete question. I answered from a general geographic point of view.
Answer:
D. highland
Step-by-step explanation:
Remember, we are told that on the thematic map, A is the Rocky Mountain region.
Since the term "mountain" is often synonymous with "highland," it is, therefore logical to conclude that the letter A would be referring to a highland climate region. In other words, it is referring to the climate of the Rocky Mountain (which can also be called a highland).