Answer:
A. True
Step-by-step explanation:
During the Mesozoic era, western North America was a highly dynamic region, characterized by intense tectonic activity. The region was subjected to a series of complex geologic processes such as sea-floor spreading, subduction, volcanic eruptions, and mountain building events. As a result of these geologic processes, several suspect terranes got accreted to the western margin of North America, including volcanic arcs, fragments of distant continents, and pieces of oceanic plateaus.
The process of accretion refers to the addition of crustal material to a continent or terrane. Accretion can occur when one tectonic plate subducts beneath another, causing the overlying sedimentary or volcanic material to be scraped off and added to the edge of the overriding plate. In the case of western North America during the Mesozoic era, the accretion of suspect terranes happened due to the subduction of the Pacific Plate beneath the North American Plate, causing the volcanic arcs and other oceanic crustal material to be scraped off and accreted onto the edge of the continent. This process continued for millions of years until the present-day configuration of the western margin of North America was formed.