Which word describes the water stored below Earth's surface? floodplain
groundwater
kettle
sinkhole

ground water

Explanation:

kettle is a thing that holds water and is used to boil it, a food plain is a field in which we grow crops on, and a sink hole is when the earth collapses on its self, therefore by using the process of elimination you can see that it is groundwater, also it's s of explanatory because of the name

i think the answer is

mass

not too sure but maybe in the hot springs.