Explanation: An ammeter measures current by directing a portion of the circuit's current through its sensitive internal meter movement. A shunt is a precisely calibrated, low-resistance resistor placed in parallel with this meter movement. When a shunt is used, most of the current flows through the shunt (the path of least resistance), bypassing the delicate meter movement. Only a small, proportional fraction of the total current goes through the meter movement itself. This allows the ammeter to measure much larger total currents than its internal movement could otherwise safely handle, effectively *increasing its indicating range*. The relationship between the shunt resistance and the range extension is indeed almost inversely proportional: a smaller shunt resistance allows more current to bypass the meter, leading to a larger total current measurable. Options A is incorrect because a shunt increases, not decreases, the meter's range. Option C is incorrect; shunts are fundamental components for extending the range of ammeters, especially analog types. Therefore, D is also incorrect.