Answer:
The 3p electron in M has jumped down to a lower energy state
Step-by-step explanation:
L - 1s² 2s²2p⁶ 3s²
M - 1s² 2s²2p⁶ 3s3p
L and M have the same number of electrons, so they are atoms of the same element.
Atom M is an excited state of atom L.
Either atom L has been excited to atom M or atom M has dropped to the ground state to form atom L.
A is wrong. Both atoms have two 2p electrons.
B is wrong. Atom L has no 3p electrons.
C is wrong. The 3s electron of atom L is already in its lowest energy state.