Hi Friend
The answer is B
A radio transmitter is an electronic device that, with the help of an antenna, radiates electromagnetic waves that contain (or may contain) information, as in the case of radio, television, mobile phone signals or any other type of radio communication.
Oscillator
In charge of generating the carrier frequency (a). In general, it will be a crystal oscillator, to guarantee the accuracy and purity of the generated frequency. In special cases it could be referenced to an atomic clock.
Audio Preamplifier
It is a low-power audio amplifier to raise the very low-level signal (c) generated, in the case of the figure by a microphone, although it could come from any other low-level signal source to obtain a level signal top (d) with which to attack the modulator amp.
Modulator amplifier
It is in charge of generating a signal (e) that will modulate the carrier wave. That is, it will vary the amplitude of the carrier wave so that it changes in accordance with the level variations of the modulating signal, which is the information to be transmitted.
Radio frequency amplifier
The radio frequency amplifier fulfills two functions, on the one hand it raises the level of the carrier (a) generated by the oscillator and on the other it serves as a separating amplifier to ensure that the oscillator is not affected by variations in voltage or impedance in the stages of power.
RF Power Amplifier
In this amplifier, the signal power (b), generated in the preceding stage, is raised to the levels required by the design to be applied to the antenna. This stage is also where the modulating signal (e) is applied, obtained at the output of the modulating amplifier to finally obtain the antenna signal (f).
Power supply
The Power Supply is the device in charge of generating, from the external supply, the different voltages required by each of the preceding stages.
I hope it helps. Thanks you
