Answer:
the only correct answer is: Photons of lower-frequency light don't have enough energy to eject an electron
Step-by-step explanation:
This question is in the model of the photoelectric effect, where some electrons are expelled from the metal by the action of a ray of light.
This effect was explained by Einstein supposes that the light rays are formed by photons and the energy of these photons is given by the Planco relation
K = h f - Ф
where K is the kinetic energy of the ejected electrons and Ф is the work function, it keeps the electrons inside the material.
When analyzing this expression there is a minimum frequency (threshold) for which K = 0
hf = Ф
Below this frequency the photons in the light beam do not have the energy to expel the electrons from the material.
Let's examine the answers
a) True. You agree with the above
b) False. The analysis is in terms of individual shock
c) False. The expulsion does not have to do with the number of photons but with the energy of each one
therefore the only correct answer is: Photons of lower-frequency light don't have enough energy to eject an electron