Final answer:
Option c) 1s²-2s²-2p³-3s¹ is the electron configuration of an excited oxygen atom as it shows an electron has been promoted to a higher energy level than in the ground state. The correct option is (C).
Step-by-step explanation:
The electron configuration of an oxygen atom in its ground state is 1s²2s²2p⁴. An excited oxygen atom is one where one or more electrons have moved to a higher energy level than in the ground state.
From the options provided, option c) 1s²-2s²-2p³-3s¹ could represent an excited state of oxygen because it shows an electron has been promoted from one of the 2p orbitals to the next higher available orbital, which is 3s.
This leaves one 2p orbital with an unpaired electron, and adds an electron to the 3s level, which would otherwise be unoccupied in the ground state.