Changes in the appearance of emission and absorption spectrums are caused by the activities of electrons.
When you transmit an amount of light on atoms, the state of the energy of electrons will become higher. Why? Because it is absorbing the light's energy. Not all wavelengths will be absorbed by the atoms, only selective.
I hope that the explanation is enough to prove that it is the correct answer. Have a nice day!
The molar concentration of the solution.
