Question

assertion (a): an ammeter has a low resistance. reason (r): because it does not change the resistance of the circuit.​

Answer 1

Ammeters are connected in series, so their resistance value is kept low enough because in series they measure the current passing through them so low resistance helps ammeter to detect the accurate value of current.

so we can say Ammeter should have low resistance so that it doesn't change the main current in the circuit