Final answer:
The most prevalent climate type over the largest portion of the interior western United States is a Type B (Dry or Arid) climate, characterized by low rainfall and high temperatures during the day.
Step-by-step explanation:
The climate type that is most prevalent over the largest portion of the interior western United States is a Type B (Dry or Arid) climate.
This climate is characterized by low rainfall and high temperatures during the day, with cooler temperatures at night or during the winter season. The terrain in Type B climates can range from sand deserts to prairie grasslands or steppes, and they typically have fewer trees compared to other climate areas.
Examples of regions in the interior western United States with Type B climates include the Great Plains and parts of Texas, New Mexico, and Arizona.