A fuse is used in main electric supply as a safety device. Which one of the following statements about the fuse is correct?

1. The question asks for the correct statement about an electrical fuse used as a safety device. 2. A fuse is designed to protect electrical circuits from overcurrents. 3. Option (A): A fuse is connected in series with the circuit it protects, not in parallel with the main switch. Incorrect. 4. Option (B): Fuses are typically made from alloys with a low melting point, like tin-lead alloys, not silver alloys (which have higher conductivity and melting points). Incorrect. 5. Option (C): The essential characteristic of a fuse wire is that it must have a low melting point. When the current exceeds a safe level, the heat generated (I²R) melts the fuse wire, breaking the circuit. Correct. 6. Option (D): A fuse wire must have low resistance to minimize power loss during normal operation, but high enough resistance combined with the current to generate sufficient heat to melt at the desired overcurrent level. 'Very high resistance' is generally not desired, as it would cause significant voltage drop and power loss normally. The key property is the low melting point. Incorrect. 7. Therefore, the correct statement is that a fuse must have a low melting point.