The correct answer is A. n-type.
A MOSFET (metalâoxideâsemiconductor field-effect transistor) is a type of transistor that uses a metal oxide semiconductor to create an insulated gate between the source and drain terminals. The source and drain are doped with n-type material, which means that they have an excess of electrons. The gate is doped with p-type material, which means that it has a deficiency of electrons. When a voltage is applied to the gate, it creates an electric field that attracts electrons from the source to the drain. This flow of electrons is the current that is controlled by the MOSFET.
Option B is incorrect because the drain is also doped with n-type material. Option C is incorrect because the source and drain are not doped with both n-type and p-type material. Option D is incorrect because the source is doped with n-type material.