The correct answer is: C. Semi-conductor
Semiconductors are materials that conduct electricity better than insulators but not as well as conductors. They are used in a wide variety of electronic devices, including computers, cell phones, and solar panels.
Semiconductors are made of materials that have four valence electrons. Valence electrons are the electrons in the outermost shell of an atom. In a semiconductor, these four valence electrons are shared between two atoms. This means that each atom has only three valence electrons, which is not enough to form a covalent bond. As a result, the electrons in a semiconductor are free to move around.
When a semiconductor is heated, the electrons move around more quickly. This makes it easier for them to conduct electricity. However, if the semiconductor is cooled, the electrons move around more slowly. This makes it more difficult for them to conduct electricity.
Insulators are materials that do not conduct electricity. This is because the electrons in insulators are tightly bound to the atoms in the material. As a result, they cannot move around freely and cannot conduct electricity.
Superconductors are materials that conduct electricity with no resistance. This means that a current can flow through a superconductor without any loss of energy. Superconductors are only found at very low temperatures.
Metallic conductors are materials that conduct electricity very well. This is because the electrons in metallic conductors are free to move around. As a result, they can easily carry an electric current.