Passage: This description is simplified. Sub-regions such as the Iberian Peninsula and the Italian Peninsula contain their own complex features, as does mainland Central Europe itself, where the relief contains many plateaus, river valleys and basins that complicate the general trend. Sub-regions like Iceland, Britain, and Ireland are special cases. The former is a land unto itself in the northern ocean which is counted as part of Europe, while the latter are upland areas that were once joined to the mainland until rising sea levels cut them off.

Question: Iceland Britain and waht other region is refered to as a special case?
Ireland