Final answer:
Portugal is the non-Mediterranean nation on the Iberian Peninsula that shares a border only with the Atlantic Ocean. Option a is the correct answer among the given option .
Step-by-step explanation:
The non-Mediterranean nation on the Iberian Peninsula that is being referred to is Portugal. Portugal shares the Iberian Peninsula with Spain, Andorra, and Gibraltar, however, unlike Spain which has both Atlantic and Mediterranean coastlines, Portugal only has an Atlantic coastline.
The Mediterranean Sea borders many countries considered part of Southern Europe, but Portugal is an exception to this due to its geographical location.
So Option a is the correct answer among the given options.