If meter A requires 100 mA to give full-scale deflection, meter B requires 50 mA to give scale deflection and meter C requires 80 mA to give full-scale deflection, then the

Concept:

In ammeters, the sensitivity 

\(S = \frac{1}{{{I_{fsd}}}}\)

Ifsd is the full-scale deflection in amps

It is expressed in ohm/volt

Calculation:

For Meter A

I_fsd = 100 mA 

\(S_A = \frac{1}{{{I_{fsd}}}}=\frac{1}{100 \ mA}\)

S_A = 10

For Meter B

Ifsd = 50 mA 

\(S_B = \frac{1}{{{I_{fsd}}}}=\frac{1}{50 \ mA}\)

SB = 20

Hence, Meter B is more sensitive.

For Meter C

Ifsd = 80 mA 

\(S_C = \frac{1}{{{I_{fsd}}}}=\frac{1}{80 \ mA}\)

SC = 12.5