For safety, the fuse wire used in the mains for household supply of electricity must be made of metal having

The correct answer is D. low melting point.

A fuse wire is a safety device that is used to protect electrical circuits from overloading. It is a thin wire that is made of a metal with a low melting point. When there is an overload in the circuit, the fuse wire melts and breaks the circuit, preventing damage to the electrical system.

The other options are incorrect because:

• A metal with a high specific heat would absorb a lot of heat before melting, which would not be effective in protecting the circuit from overloading.
• A metal with a high melting point would not melt easily, which would not be effective in protecting the circuit from overloading.
• A metal with a high resistance would cause a lot of heat to be generated in the circuit, which could lead to an overload.