An ampere ammeter is a tool for calculating direct or indirect electrical power. The ammeter can measure a wide range of current values ​​as only a limited portion of the current is directed to the meter system at high values; most of it is carried by the parallel shunt and meter.
There is a pointer to the phone for some types of ammeter, but most have a digital monitor. We must connect the ammeter to the series with it to calculate the current flowing in the circuit section.
Given,
Ammeter width I =0−2A
Number of stages in scale n = 20
We know that,
Minimum ammeter = $\frac{ammeter width }{ number of sections on the scale}$
L.C = $\frac{2}{20}$ = 0.1A
Therefore, the minimum calculation is 0.1A per phase.
Therefore, option C is correct.

When taking an ammeter's least count, a number of considerations should be kept in mind. For the measurement to be accurate, there should be no inaccuracy. When the ammeter is detached from the circuit and the pointer is precisely at zero, the instrument has a zero error. The zero error is negative if the pointer is above the zero line. The reading must be reduced by the quantity of divisions above the zero line.