Correct Option (C)
A Compact Disc (CD) audio player utilizes a laser beam to reproduce sound. The laser beam scans the microscopic pits and lands on the CD's surface. These variations in the surface reflect the laser light differently, and a photodetector converts these reflections into electrical signals. These electrical signals are then processed and converted into audible sound. This optical method allows for non-contact reading of the data, minimizing wear on the disc.
Incorrect Options:
Quartz crystals are primarily used in electronic oscillators for precise timing and frequency control, such as in watches and radios, due to their piezoelectric properties. They are not employed in the sound reproduction mechanism of a CD player.
A titanium needle is associated with older phonograph or record players, where a physical stylus tracks grooves on a vinyl record to produce sound. This technology is distinct from the optical reading method used by CD players.
Barium titanate ceramic is a ferroelectric material known for its high dielectric constant and piezoelectric properties. It is used in applications such as capacitors, transducers, and sensors. It does not play a role in the sound reproduction process of a CD player.