What event will most likely occur at a divergent plate boundary

Rift valley or Mid-ocean ridge.

Explanation:

Rift valley or Mid-ocean ridge will most likely occur at a divergent plate boundary.

Rift valley are formed at where Earth's tectonic plates rifts and it's a lowland region found both at the bottom of oceans as a result of seafloor spreading and on land.

Examples are the Rhine Rift valley and Baikal Rift valley.

The Mid-ocean ridge is a seafloor or underwater mountain range formed where tectonic plates pull away from each other at a divergent plate boundary. It is approximately about 65,000 kilometers deep.

Examples are the East pacific ridge and Mid-Atlantic ridge.