Answer : The correct option is, (B) Germanium
Explanation :
As we know that the material are divided into three categories which are conductors, insulators and semiconductors.
Conductors : It is a type of substance which conduct electricity that means it allow the electrons to flow through them.
Example of conductors are, iron, aluminium, gold, etc.
Insulators : It is a type of substance which does not conduct electricity that means it does not allow the electrons to flow through them.
Examples of insulators are, glass, rubber, ceramics, etc.
Semiconductors : It is a type of substance which conduct electricity under certain conditions that means it allow the electrons to flow through them. The conductivity level of semiconductors lie between the conductors and the insulators.
The good examples of semiconductors are silicon, germanium, gallium, and selenium.
In the given options, aluminium, gold are the metals which conduct electricity and concrete is an insulator which do not conduct electricity while the germanium is the good semiconductor.
Hence, the correct option is, (B) Germanium