In which sentence is the underlined phrase an adverb prepositional phrase?

The biggest industry of the Cook Islands is tourism, which brings in more revenue than exporting fish and fruit.

An airport on Rarotonga is a destination for tourists to the Cook Islands.

The Cook Islands is a group of 15 small volcanic islands.

The Cook Islands stretch over 800 miles.

An airport on Rarotonga is a destination for tourists to the Cook Islands.