The oceanic Pacific plate and the oceanic Juan de Fuca plate are diverging. Which landform would you expect to form? a mid-ocean ridge
a volcanic island arc
a rift valley
a non-volcanic mountain chain
a volcanic mountain arc

The landform that will form is a mid-ocean ridge.

Explanation:

When tectonic plates move away from each other they form a divergent plate boundary. At this type of boundary, as the plates move away, a gap starts to open up gradually. This gap becomes wider and wider over time and the crust is made much less thick, which in turn presents a good opportunity for the magma to come out on the surface.

Because the crust is weaker and thinner, the magma manages to rise through it and rich the surface relatively easily. As it does, the magma reaching the surface, or rather the bottom of the ocean, it solidifies in the water and as more and more magma comes out it piles up. By piling up and constantly creating new rock an underwater mountain chain starts to form and this type of mountain chain is known as a mid-ocean ridge.