Name the region in Australia primarily known for its Shiraz wines.

The Barossa Valley is renowned for its Shiraz wines due to its ideal climate and soil conditions that favor this varietal. The region is characterized by a warm climate that allows Shiraz grapes to ripen fully, resulting in wines that are rich, bold, and often exhibit complex flavors of dark fruit, chocolate, and spicy notes. It has a long history of Shiraz production, with many vineyards being several decades old, contributing to the depth and character of the wines.

In contrast, Margaret River, while known for producing high-quality wines, is more famous for its Cabernet Sauvignon and blends. The Yarra Valley is recognized for its cooler climate, which is better suited for Pinot Noir and Chardonnay. Coonawarra is distinguished for its Cabernet Sauvignon as well, particularly known for its terra rossa soils that provide unique growing conditions. Each of these regions has its own specialties, but the Barossa Valley stands out specifically for its Shiraz, making it the correct choice in this context.