Choose the correct letter, A, B or C. Where is the water taken from?

Many people have asked what the Rest House was for. Was it a place for pilgrims to stay? Was it a meeting hall of some kind? Perhaps the most likely answer to this question is that its purpose is purely aesthetic, to act as a visual balance for the mosque and to preserve the symmetry of the design of the whole complex.
Let’s have a look at some of the engineering features of the garden. For one thing, they require a constant supply of running water. When it was built, water was drawn from the river manually, using an elaborate rope and bucket system, pulled by a team of bullocks. The water was then brought through a broad water channel and held in a number of supply tanks. These tanks were at varying  heights  off the  ground  and  were  ingeniously  designed to store the very large amounts of water required. Using an elaborate system of underground pipes, the water was then distributed from the supply tanks to each of the fountains. To ensure that the water pressure was the same throughout the garden, there was a copper pot under each fountain connected to the water supply. It was undoubtedly a brilliant system.