You are given a set of six nations that have something in common. You are also given five groups of three nations each. Your task is to determine which one of those five groups can be added to the set. All three nations in the selected group will share the same characteristic as the six nations in the set. None of the nations in the remaining four groups will have that characteristic.

Set) Bulgaria, Finland, Hungary, Italy, Japan, Romania

Group A) Albania, Germany, Thailand
Group B) Chile, Portugal, Spain
Group C) Denmark, Egypt, Norway
Group D) Kuwait, Laos, Zaire
Group E) Mexico, United States, Venezuela