The electron configuration provided is 1s² 2s² 2p⁶ 3s² 3p⁵.

The outermost energy level (principal quantum number n = 3, or the third shell) contains the valence electrons.

To find the number of valence electrons, the electrons in the 3s and 3p sub-shells are summed: 2 + 5 = 7 valence electrons. Elements with 7 valence electrons in their outermost shell belong to Group 7 (or Group 17 in modern IUPAC notation) of the periodic table, known as the halogens.

The element with this configuration is chlorine (atomic number 17).

The correct option is A - Group 7