Over 70 million years ago, the tectonic movements that caused the formation of the Rocky Mountains in a series of pulses during a mountain-building process known as the Laramide orogeny also resulted in the creation of the volcanic system known as the Coast Range Arc.

A. Over 70 million years ago, the tectonic movements that caused the formation of the Rocky Mountains in a series of pulses during a mountain-building process known as the Laramide orogeny also resulted

B. Caused by tectonic movements in a series of pulses, the Laramide orogeny, which is the process through which the Rocky Mountains were formed over 70 million years ago, also resulted

C. The Laramide orogeny, a mountain-building process of the Rocky Mountains, caused by tectonic movements in a series of pulses over 70 million years ago, also resulted

D. Over 70 million years ago, the tectonic movements causing the formation in a series of pulses of the Rocky Mountains during a mountain-building process known as the Laramide orogeny, also resulting

E. The Rocky Mountains, formed over 70 million years ago during the mountain-building period process known as the Laramide orogeny, caused by tectonic movements in a series of pulses, resulted

OA A

Source: Economist Gmat