Question

new oceanic crust is formed at _________.
divergent boundaries by submarine eruptions and intrusions of basaltic magma
divergent boundaries by submarine eruptions and intrusions of rhyolitic magma
convergent boundaries by submarine eruptions and intrusions of basaltic magma
convergent boundaries by submarine eruptions and intrusions of rhyolitic magma
transform boundaries by submarine eruptions and intrusions of rhyolitic magma
transform boundaries by submarine eruptions and intrusions of basaltic magma

Explanation:

New oceanic crust is formed at divergent plate boundaries. Basaltic magma is involved in the process through submarine eruptions and intrusions. Rhyolitic magma is more associated with convergent - boundary volcanic activity. Convergent and transform boundaries are not the sites of new oceanic crust formation.

Answer:

Divergent boundaries by submarine eruptions and intrusions of basaltic magma