The groundwater stored between layers of hard rocks below the water table is known as:

Correct option is B

The correct answer is Aquifer.
Groundwater is the water found under the ground in soil spaces, cracks of earth's crust etc
The presence of groundwater in soil enables the plant to take it up to fulfil its water requirements. It also indicates a healthy soil. Groundwater is the main source of drinking water as well as irrigation in many parts of the country.
The rainwater and water from other sources such as rivers and ponds seeps through the soil and fills the empty spaces and cracks deep below the ground. The process of seeping water into the ground is called infiltration. The groundwater thus gets recharged by this process. At places, the groundwater is stored between layers of hard rock below the water table. This is known as an aquifer. Water in the aquifers can be usually pumped out with the help of tube wells or handpumps. Thus, the groundwater stored between layers of hard rocks below the water table is known as aquifer.