The correct statement about a flowing artesian well is that the potentiometric surface lies above the ground surface, allowing water to flow naturally without the need for pumping.
The statement that is correct in reference to a flowing artesian well is c) the potentiometric surface in the region of the well lies above the ground surface. In a flowing artesian well, the pressure within the aquifer is high enough to push water to the surface without the need for pumping.
This occurs when the potentiometric surface (the level to which water will rise in a well due to pressure in the aquifer) is above the ground level. Hence, water flows out of the well on its own. This situation often arises when there is an inclined layer of impermeable rock that confines the aquifer at a lower elevation than where the well is drilled.
So, when the potentiometric surface is above the ground surface, a true artesian condition exists, which allows water to flow out of the well naturally without any mechanical aid.