Elements with complete electron shells are most likely noble gases which have 8 valence electrons in their outer shell. So the letter farthest to the right should be the correct answer. Noble gases are found in group 18
The p block elements involve group III A, IV A, V A, VI A , VII A and VIII A. But among these groups, there are only Nobel gases that have complete valence shell electrons.
The Nobel gases have their complete valence shell electrons due to which they are least reactive and stable one. They are found in VIIIA group of the periodic table at right side.
