Final answer:
The 'Fertile Belt' in the West likely refers to areas with abundant rainfall due to the rain shadow effect, making them suitable for agriculture, which corresponds to option 'a. High precipitation'.
Step-by-step explanation:
The term 'Fertile Belt' is not a widely recognized geographical term; however, based on the context of the provided information regarding regions with high precipitation and suitability for agriculture due to the rain shadow effect, it could be inferred that the 'Fertile Belt' in the West refers to areas that receive abundant rainfall, making them favorable for agriculture. This means that the western United States, west of the mountain ranges, tends to have more precipitation due to the air rising over the mountains, causing water vapor to condense and fall as rain or snow, which is then followed by drier conditions on the eastern side due to the rain shadow effect. Since the question addressed 'the Fertile Belt in the West', the most correct choice based on the information would likely be option 'a. High precipitation', although the term 'Fertile Belt' would need further clarification to provide a definitive answer.