Final answer:
The statement that an artesian well or spring requires a confined aquifer is true, as the confined nature of the aquifer and the pressure within are what allow water to flow naturally without pumping. Option a is the correct answer.
Step-by-step explanation:
An artesian well or spring does indeed require a confined aquifer, making the statement true. A confined aquifer is necessary because it is contained within impermeable layers of rock or sediment (aquitards) that prevent the free mixing of water. The pressure exerted by the layers above pushes the water up naturally when a well reaches into this type of aquifer. This is what causes the water to flow without the need for a pump and defines the 'artesian' condition.
Confined aquifers are typically found deep below the Earth's surface and can be the safest source of drinking water, as they are often protected from surface contaminants, including pathogens. In contrast, unconfined aquifers are more susceptible to pollution because they have a direct connection with the Earth's surface, hence they are not typically used for artesian wells.
Furthermore, it's important to consider sustainable practices and water management when drilling into aquifers, whether confined or unconfined. Groundwater is a critical resource, but it's not considered a renewable one on a human timescale. Over-extraction can lead to depletion of aquifers, lowering of the water table, and long-term environmental impacts.