The correct answer is: B. moderately
The base of a transistor is a semiconductor region that is sandwiched between the emitter and collector regions. It is typically doped with a concentration of impurities that is between the concentrations of the emitter and collector regions. This allows the base to control the flow of current between the emitter and collector regions.
A heavily doped base would have a high concentration of impurities, which would make it more conductive. This would reduce the transistor’s ability to control the flow of current. A lightly doped base would have a low concentration of impurities, which would make it less conductive. This would also reduce the transistor’s ability to control the flow of current.
A moderately doped base has an intermediate concentration of impurities. This allows it to control the flow of current more effectively than a heavily doped or lightly doped base.