Question

at which boundary is new crust created as molten material erupts from the mantle to the ocean floor?
the mid - ocean ridge
all plate boundaries
transform boundaries
convergent boundaries

Explanation:

New crust is formed at divergent plate boundaries. The Mid - Ocean Ridge is a divergent boundary where molten material from the mantle erupts to the ocean floor to create new crust. Transform boundaries slide past each other and convergent boundaries involve one plate moving under another or colliding, neither creating new crust.

Answer:

the Mid - Ocean Ridge