Question

Which of the following have what could be considered brackish waters? Oceans, aquifers, lakes, or marshes?

Answer 1

Marshes.

Explanation:

This one could also be done by "elimination". What is "brackish water"? It is partly-salty - neither fresh nor ocean water.

So, it is not aquifers, which are underground freshwater layers. It is not Lakes, which are large fresh-water bodies. And it is not oceans - the large salt-water bodies of the earth.

Marshes are those wetlands between the run-off of freshwater from land and the saltiness of the sea. A mixture of both creates an "in between" salinity with its own unique ecosystem of plants and animals. This is "brackish" water.