Final answer:
Tin (c) is the metal with a relatively low melting point used in fire detection systems and electrical fuses, due to its ability to form a protective oxide layer and its low melting point. Therefore, correct option is c.
Step-by-step explanation:
The metal that is used in fire detection and extinguishing devices as well as in electrical fuses and has a relatively low melting point is tin (c). Tin is known for its ability to form a protective oxide coating on its surface which helps to prevent further oxidation, a process known as passivation.
The common ore of tin is cassiterite, and to separate tin from it, the ore is crushed and then concentrated by various methods including flotation and gravity separation. Finally, tin is usually obtained by reducing the ore with coal in a furnace.
Tin's low melting point and protective oxide coating make it ideal for use in safety devices where a predetermined temperature threshold, when surpassed, will melt the tin, breaking a circuit or triggering sprinklers, ensuring safety from fires or electrical overloads.