What is an aquifer? a. a river dam b. a natural underground water supply c. an environmental hazard caused by drilling d. a state agency that monitors water usage (the answer is B, i just wanted to put the question)

a natural underground water supply

Explanation:

An aquifer is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials (gravel, sand, or silt). Groundwater can be extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology.

herodotus taught this. herodotus was an ancient greek historian who was born in halicarnassus in the persian empire. he is known for having written the book the histories, a detailed record of his "inquiry" on the origins of the greco-persian wars.

this isn't a question and if you're going to list things be kind and use commas.