Which of the following is a well-known producer of Coonawarra?

Parker Estate is recognized as a well-known producer of Coonawarra wines, particularly noted for its exceptional Cabernet Sauvignon. Coonawarra, located in South Australia, is famous for its terra rossa soil, which plays a significant role in producing high-quality wines that showcase intense fruit flavors and structure. Parker Estate has made a name for itself in this region by consistently crafting wines that reflect the unique terroir of Coonawarra, becoming a standout brand among both critics and consumers.

While other choices like Penny’s Hill and Yalumba contribute significantly to Australian winemaking, their reputations may not be as tightly associated with Coonawarra specifically. Penny’s Hill is situated in the McLaren Vale district, and Yalumba is noted for its Barossa Valley and Eden Valley wines. Chateau Tanunda also operates in the Barossa region and, while prestigious, is not a cornerstone of the Coonawarra identity. Thus, Parker Estate's prominence in Coonawarra firmly establishes it as the correct answer in this context.