The silurian period occurred                a.  during the hadean eon.      b.  before the neogene period.      c.  during the mesozoic era.      d.  after the permian era.

We know that the Silurian period gave way to the Devonian period, which is when the Neogene era started, therefore:

The answer is B. before the Neogene era.

Hope it helped,

BioTeacher101

the oceanic zone is typically defined as the area of the ocean lying beyond the continental shelf, but operationally is often referred to as beginning where the water depths drop to below 100 meters (328 feet), seaward from the coast to the open ocean.

explanation: