Which specific kind of wine did Chuck Wagner focus on establishing a reputation for?

Chuck Wagner is best known for his focus on Cabernet Sauvignon, particularly through his work with the iconic Napa Valley winery, Caymus Vineyards. Since establishing the winery with his family in the early 1970s, Wagner has been instrumental in elevating the profile of Cabernet Sauvignon, showcasing the grape's potential for producing rich, fruit-forward wines with depth and complexity. His approach often emphasizes ripe fruit flavors, balanced acidity, and smooth tannins, setting a high standard for this varietal.

Under his stewardship, Caymus gained widespread recognition and acclaim, contributing to the popularity of California Cabernet Sauvignon on both a national and international level. This reputation was further solidified by various award-winning vintages, reinforcing Wagner's name with this particular grape variety. His dedication to quality and innovation in Cabernet Sauvignon continues to influence the wine industry today, making it clear why this is the correct answer.