Final answer:
Option A.
The Mountains and Basins region is best described by the statement that it lies mostly to the west of the Pecos River. This correctly identifies the location based on the geographic features described.
Step-by-step explanation:
Based on the provided descriptions, the correct statement that best describes the location of the Mountains and Basins region is: a. Lies mostly to the west of the Pecos River.
This region is characterized by rugged mountain ranges and significant basin topography.
While the other options might describe geographic features or locations in other contexts, they do not accurately describe the Mountains and Basins region in relation to the given details.
It is important to correlate the information from maps and geographic descriptions to identify the location of such regions accurately.
Remember that geographic features such as rivers, mountains, and basins work as landmarks to determine the location of broader regions. Please mention the correct option in the final answer when providing your responses.