The correct answer is option 1, North East Australian Coast. This region is home to the largest barrier reef system in the world known as the Great Barrier Reef. Located off the coast of Queensland in northeastern Australia, it stretches over 2,300 kilometers (1,400 miles) and is composed of nearly 3,000 individual reefs.

Option 2, West Australian Coast, is not correct as the largest barrier reef system is not found in this region. Option 3, North Australian Coast, is also incorrect as the Great Barrier Reef is specifically located along the northeastern coast, not the entire northern coast. Option 4, South Australian Coast, is not correct either as the Great Barrier Reef is not found in the southern portion of Australia.

It is important to note that the Great Barrier Reef is not only the largest barrier reef system in the world but is also a UNESCO World Heritage Site and is renowned for its exceptional biodiversity.