Correct option is A
Ammeter, instrument for measuring either direct (DC) or alternating (AC) electric current, in amperes.
An ammeter can measure a wide range of current values because at high values only a small portion of the current is directed through the meter mechanism; a shunt in parallel with the meter carries the major portion.
Ideally, an ammeter should have very low internal resistance.
This minimizes the change in circuit behavior due to the insertion of the ammeter.
If the ammeter had significant resistance, it could reduce the current flowing in the circuit, affecting the measurement and the circuit's performance.
To measure the current, generally, the ammeter is connected in series with the circuit. This device is mainly used for measuring a small amount of current, and the current is measured in the milliampere or microampere range.
The device which is used to measure the current in milliamperes is known as a milliammeter, and the device for measuring extremely small electric currents, calibrated in microamperes is called a microammeter. In a circuit, the ammeter is represented by the letter "A".
