Question

which is the first step in the seafloor spreading process?
a crack forms in oceanic crust.
volcanoes erupt under the ocean.
molten rock rises up through the crust.
dense plates are subducted under less dense plates.

Explanation:

Seafloor spreading begins when a crack forms in the oceanic crust, allowing magma to rise. This crack is the starting - point for the process. Volcanoes erupting, molten rock rising, and plate subduction occur later in related tectonic processes but are not the first step.

Answer:

A. A crack forms in oceanic crust