To which country do the Cook Islands belong?

Explanation

The Cook Islands is a self-governing parliamentary democracy in free association with New Zealand. The islands have around 20,000 inhabitants and area of 240 km², spread over 15 islands. The capital Avarua is on the island Rarotonga. The Cooks Islands were first inhabited around year 600 by Polynesians migrating from Tahiti. The first Spanish ships arrived in the 1600s, and it became a British protectorate in 1888 out of its own free will.