the answer is a!! its pretty simple I just read the graph.
When you know both the speed and direction of an object’s motion, you know the velocity of an object. speed in a given direction is called velocity
hope this helps :)
Answer:
photoelectric effect
Explanation:
When the energy from photons is absorbed by matter, the matter can emit electrons. This process is called the photoelectric effect. The photoelectric effect is a property of light that is not explained by the theory that light is a wave.