Beneath Some Valleys in East Africa and in a Large

Beneath some valleys in East Africa and in a large area called the Basin and Range Province in the western United States and northern Mexico, the crust ____.

A) appears to be in the initial stages of rifting
B) appears to have undergone numerous earthquakes in the last 1000 years
C) is much thicker than it is in the surrounding areas
D) is composed mostly of basalt
E) is composed of fragments of extinct volcanoes