Question

which one of the following is the best materials for making connecting wires?

Answer 1

Well, it seems you have not provided the options.
But the copper is most commonly used material for making wire this is because not only it is the good conductor of electricity but also the cheap so economical to use.
Also the silver can also be used for making the wire because it is also a good conductor but as this more expensive so does not used most often as compared to copper  But it is used for the coating in copper wires in order to improve the protect it from corrosion and more good skin conductivity  . Just like the copper it is also easily soldered.

Answer 2

Well, it seems that you have not provided the options, so I am giving general answer to your question.
The materials which are commonly used to make connecting wires are
1. Copper
2. Zinc
3. Aluminium
4. Silver
The most appropriate material which is used widely is copper. The reason is that it is a very good conductor of electricity. It has a very good maliability and ductility due to which it can easily be bended and molded.
Since, metals are crystalline. Hence monocrystalline copper or aluminium has better conductivity then polycrystalline metals.