The grammatical number of "Newfoundland and Labrador"

Solution 1:

Saint Vincent and the Grenadines is a multi island Anglo-Caribbean country in the Lesser Antilles island arc...

Saint Kitts and Nevis is an island country in the West Indies.

The Archipelago of San Andrés, Providencia and Santa Catalina is one of the departments of Colombia.

The Turks and Caicos Islands are a British Overseas Territory consisting of the larger Caicos Islands and smaller Turks Islands,...

Carriacou and Petite Martinique, also known as the Southern Grenadines, is a dependency of Grenada,...

Antigua and Barbuda is an island sovereign state in the West Indies in the Americas

And by the way

The Papal States were a series of territories in the Italian Peninsula under the direct sovereign rule of the Pope,