The correct answer is (a). Solder is an alloy of tin and lead. It is a low-melting point alloy that is used to join metals together. Tin is a soft, silvery-white metal that is easily melted. Lead is a heavy, dense metal that is also easily melted. When tin and lead are combined, they form an alloy that is both strong and easy to work with. Solder is used in a variety of applications, including electronics, plumbing, and jewelry making.
Option (b) is incorrect because solder does not contain copper. Copper is a red metal that is used in a variety of applications, including electrical wiring and plumbing. However, it is not a component of solder.
Option (c) is incorrect because solder does not contain zinc. Zinc is a blue-white metal that is used in a variety of applications, including batteries and galvanizing steel. However, it is not a component of solder.
Option (d) is incorrect because solder does not contain zinc. Zinc is a blue-white metal that is used in a variety of applications, including batteries and galvanizing steel. However, it is not a component of solder.