How does a fuse protect a toaster? a. when the current is too high, a resettable switch opens the circuit. b. when the resistance is too high, a resettable switch opens the circuit. c. when the resistance is too high, a metal strip in the fuse melts and opens the circuit. d. when the current is too high, a metal strip in the fuse melts and opens the circuit.

The correct option is (D). i.e.When the current is too high, a metal strip in the fuse melts and opens the circuit.

Explanation: The fuse contains a small piece of wire which has very less melting point. As there is huge current flow, the wire heats to the heavy current flow & melts & the circuit is broken.
Hence, it saves the device from the heavy current flow & the device is damage free. breaks the circuit if a fault in an appliance causes too much current flow.