(i) Anannya’s answer is incorrect. Three-pin plugs are used to connect electrical appliances having metallic bodies to the earth wire, which provides a low-resistance path for leakage current and prevents electric shock. It does not reduce heating of wires.
(ii) A fuse acts as a safety device in domestic circuits. It contains a thin wire that melts and breaks the circuit when the current exceeds the safe limit, thus protecting the wiring and appliances from short circuits and overloads.