The island state of Australia is

Victoria
Queensland
Tasmania
New South Wales

The correct answer is Tasmania.

Tasmania is an island state of Australia. It is the second-smallest state in Australia, after the Australian Capital Territory. Tasmania is located 240 kilometres (150 mi) to the south of the Australian mainland, separated by Bass Strait. The state’s capital and most populous city is Hobart.

Tasmania is a popular tourist destination, known for its natural beauty, including its mountains, forests, beaches, and wildlife. The state is also home to a number of historical sites, including the convict settlement of Port Arthur.

The other options are incorrect because they are not island states of Australia. Victoria is a state in southeastern Australia. Queensland is a state in northeastern Australia. New South Wales is a state in southeastern Australia.