The theory of plate tectonics scientists explain
a. how ocean currents move over earth’s surface.
b. why hurricanes occur.
c. how earthquakes and volcanic eruptions occur.
d. why earth’s mantle is more dense than its crust.

Option (C)

Explanation:

The plate tectonic theory describes how the lithospheric plates namely, the continental plate and the oceanic plate moves over the region of asthenosphere layer. It is due to the mechanism of the convection current that generates in the mantle that forces the plates to move from one place to an other with respect to a fixed point.

This theory also explains the consequences of the plate motion. Some of them are as follows-

1) Due to the divergent plate boundary between two plates, new crusts are formed by adding more materials to it along the mid oceanic ridge. With time this small rift turns into an ocean.

2) Due to the convergent plate motion, the denser plate gets subducted below the less denser plate. As a result of which deep-focus earthquake occurs and volcanic arcs (volcanoes) as well as island arcs are formed over the overriding plates.

Thus, the correct answer is option (C).

it is b that is the answer.