Final answer:
A rift valley is formed in a divergent boundary as two tectonic plates move away from each other.
Step-by-step explanation:
The topographic feature formed in a divergent boundary is a Rift valley. A divergent boundary occurs when two tectonic plates move away from each other, creating a gap. As the plates separate, magma rises to fill the gap, often forming a long, narrow valley called a Rift valley. This process can lead to the formation of new crust and the eventual creation of a new oceanic basin.
Learn more about Plate Tectonics