Which of the following types of linear voltage regulator operates by loading the unregulated voltage source?

A shunt regulator is connected in parallel (shunt) with the load. It maintains a constant output voltage by drawing variable amounts of current from the unregulated power source, effectively loading it through a series dropping resistor. As the load's current demand changes, the shunt regulator adjusts its own current draw in the opposite direction. This constant loading keeps the total current through the series resistor steady, yielding a stable voltage. Series regulators, by contrast, sit in line with the load and alter their resistance to drop voltage, without actively dumping excess current to ground to load the source.