What component extracts and amplifies desired electro-magnetic waves?

The correct choice is the receiver, which is designed specifically to extract and amplify desired electro-magnetic waves. Receivers operate by capturing incoming radio signals, which may be weak or distorted due to distance or interference. Once a signal is received, the receiver demodulates it, which means it separates the information contained in the electromagnetic wave from the carrier wave. This process is essential for recovering the original message or information encoded in the signal.

After demodulation, the receiver amplifies the signal to a level suitable for further processing or playback. This amplification is crucial because it enhances the quality and clarity of the audio or data being transmitted, making it audible or usable for the end user. Receivers are integral to various communication systems, including radio, television, and telecommunications, where the clarity and fidelity of the received signals greatly impact the overall effectiveness of the system.

The other options serve different functions. The transmitter generates and sends out radio waves, the antenna facilitates the transmission and reception of those waves, and the power supply provides energy to the electronic components but does not directly handle the extraction or amplification of signals.