A passing motorcycle causes distortion or disturbance with the reception of the signal in radio and TV. The cause of this is
A. The spark plug fitted in the engine produces electromagnetic signal due to sparking
B. The vehicle’s metal part block/distort the radio waves
C. The intense sound waves affect the small electronic devices of the receptor
D. Modern motorcycles are fitted with electric ignition system which produces radio waves

Hint: The radio waves are used as the signals in radio and TV. These are electromagnetic waves and can easily interfere with other electromagnetic waves. The electromagnetic waves can easily interfere with switching loads such as resistor, inductor,capacitor used in electric circuits, transformers etc.

Complete step by step answer:
The spark plug fitted in the motorcycle can produce electromagnetic signals due to sparking. These electromagnetic waves can interfere with other electromagnetic waves. Radio waves used in the transmission of signals in radio and TV are electromagnetic waves. Therefore it can interfere with other electromagnetic waves such as one produced by the spark plug in the motorcycles. Such interference can distort original electromagnetic waves, resulting in disturbances in the reception of the signal in radio and TV.
The correct answer is (A).

Note:
Metal can shield electromagnetic radiation effectively. However, the wavelength of radio waves is very high and it can easily cover small metal pieces in the motorcycle. Therefore option (B) is wrong.
Sound waves are longitudinal waves and electromagnetic waves are transverse waves. Therefore sound waves will not distort radio waves. Therefore, option (C) is wrong.
What can interfere with electromagnetic waves?
Switching loads like resistance, inductor, capacitance in electric motors, transformers, power supplies, heaters, lamps, etc can cause electromagnetic interference especially at currents above 2 A.