Mount St Helens and the Other Cascade Volcanoes Are_______

Mount St. Helens and the other Cascade volcanoes are_______ .

A) a row of young, active, shield volcanoes built as western North America moved over a hot spot deep in the mantle
B) young, active stratovolcanoes built on a continental margin above a sinking slab of oceanic lithosphere
C) old, deeply eroded, basaltic shield volcanoes built when western North America was over the present- day site of the Hawaiian hot spot
D) old, deeply eroded stratovolcanoes built before the Pacific Ocean existed