The correct answer is option 4, Kyushu Island, Japan. Kyushu Island is not a coral reef island.

A coral reef is a ridge or mound of living organisms called corals, which are formed due to the accumulation and growth of the calcium carbonate skeleton of the corals. These formations occur in warm, shallow, and nutrient-rich waters. Coral reef islands are the result of the accumulation of coral debris and other organic materials on top of submerged coral reefs over thousands of years.

Option 1, Great Barrier Reef in Australia, is the largest coral reef system in the world, consisting of over 2,900 individual reefs and 900 islands. It is a prime example of a coral reef island.

Option 2, Rainbow Reef in Fiji, is a popular diving site known for its vibrant coral formations and diverse marine life. It is also considered a coral reef island.

Option 3, Swaraj Island in India, also known as Havelock Island, is part of the Andaman and Nicobar Islands which lie in the Bay of Bengal. It is surrounded by rich coral reefs and is indeed a coral reef island.

Therefore, the only option that is not a coral reef island is option 4, Kyushu Island, Japan