The correct answer is B. Silicon and Germanium.
Transistors are semiconductor devices used to amplify and switch electronic signals and electrical power. They are composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor’s terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.
Silicon and germanium are both semiconductors, which means that they have electrical conductivity between that of a conductor and an insulator. They are also both elements, which means that they are made up of atoms of the same type. Silicon is the most common semiconductor material used in transistors, while germanium is less common but still used in some applications.
Boron and aluminium are both elements, but they are not semiconductors. Iridium and tungsten are both metals, and they are not semiconductors either. Niobium and columbium are both elements, but they are not semiconductors either.
In conclusion, the two elements that are frequently used for making transistors are silicon and germanium.