Answer:
The electromagnetic theory of light.
A is correct .
Step-by-step explanation:
Photoelectric effect :
When a light hits a metal then the electrons emits from the metal surface and this process is called photoelectric effect. The emitted electrons are called photo-electrons.
According to this process, we conclude that some electrons were emitted by the zinc plate when exposed to ultraviolet light.
Electromagnetic theory of light :
The particles oscillate in perpendicular to the direction of travel of the wave motion.
Light is a electromagnetic wave that can be seen by the human eyes.
All electromagnetic waves can travel through a vacuum.
Hence, The electromagnetic theory of light.