at a rift valley, new rocks fill the valley floor as the walls of the valley spread apart. a rift valley forms at a

a.
divergent boundary

b.
convergent boundary

c.
transform fault boundary

At a rift valley, new rocks fill the valley floor as the walls of the valley spread apart. A rift valley forms at a divergent boundary

Explanation:

A rift valley is a region that appears where Earth’s tectonic planes shift aside or rift. Rift valleys are seen both on land and at the bottom of the ocean, where they are formed by the process of seafloor spreading. Many rift valleys are part of “triple junctions,” a type of divergent boundary where three tectonic plates meet at about 120° angles.

A rift valley is created on a divergent plate boundary, a crustal expansion or expanding freely of the surface, which is afterward extra intensified by the effectiveness of erosion.

tissue

explanation:

it is actually formed by geoup of cells which is tissue