The maximum discharge of a tube well is about 500 liters/sec. This is because the discharge of a tube well is determined by the diameter of the well, the depth of the well, and the pumping rate. The diameter of the well is the most important factor, as it determines the amount of water that can be drawn into the well. The depth of the well also affects the discharge, as it determines the pressure of the water in the well. The pumping rate is the amount of water that is pumped out of the well per unit of time. The maximum discharge of a tube well is typically limited by the pumping rate, as the well cannot draw water faster than it can be pumped out.
Option A is incorrect, as the maximum discharge of a tube well is typically much higher than 5 liters/sec.
Option B is incorrect, as the maximum discharge of a tube well is typically much higher than 50 liters/sec.
Option C is incorrect, as the maximum discharge of a tube well is typically much higher than 500 liters/sec.
Option D is correct, as the maximum discharge of a tube well is typically about 500 liters/sec.