A moving coil galvanometer is converted into an ammeter by connecting:

1. An ammeter must carry large current yet barely disturb the circuit, so it needs very low resistance. 2. Connecting a small shunt resistance $r_s$ in parallel diverts most of the current around the coil. 3. The combined resistance becomes small (≈ $r_s$ when $R_G \gg r_s$). 4. A series large resistance would instead make a voltmeter, so that option is wrong. _Source: NCERT Class 12 Physics Ch 4 "Moving Charges and Magnetism", p.160_