In the central United States, ancient rift valleys remain from failed spreading centers and these ancient rifts today are zones of weakness whose faults can be reactivated due to long-distance effects of Atlantic plate spreading and Pacific plate collision. a) true
b) false

True

Explanation:

A rift valley is a lowland region that occurs where Earth’s tectonic plates move apart, or rift. Rift valleys are found both on land and at the bottom of the ocean, where they are created by the process of seafloor spreading. Rift valleys differ from river valleys and glacial valleys because they are created by tectonic activity and not the process of erosion.

Rift valleys can also form at transform faults, where tectonic plates are grinding past each other. The Salton Trough, which stretches through California (United States) and Baja California (Mexico), is a rift valley created in part by the San Andreas Fault.

answer; i believe that the correct answer is (d); // supercontinent

can you explain a little further maybe give multiple choice? ?