The correct answer is: A. sound waves into electrical energy.
A microphone is a device that converts sound waves into electrical signals. The electrical signals can then be amplified and transmitted to a loudspeaker, which converts them back into sound waves.
There are many different types of microphones, but they all work on the same basic principle. When sound waves hit a microphone, they cause a diaphragm to vibrate. The diaphragm is connected to a coil of wire, which is suspended in a magnetic field. As the diaphragm vibrates, it causes the coil of wire to move back and forth in the magnetic field. This movement of the coil of wire creates an electric current.
The strength of the electric current is proportional to the amplitude of the sound waves. This means that louder sounds will create a stronger electric current, and softer sounds will create a weaker electric current.
The electrical signals from a microphone can be amplified and transmitted to a loudspeaker. The loudspeaker converts the electrical signals back into sound waves by moving a cone back and forth in a magnetic field. The movement of the cone creates sound waves that are identical to the original sound waves that were picked up by the microphone.
Options B, C, and D are incorrect because microphones do not convert sound waves into light rays, electrical energy into sound waves, or sound waves into magnetic currents.