Which major agricultural product is California known for growing?

California is renowned for its production of grapes, which play a significant role in the state's economy and agriculture. The state's diverse climates and rich soils create ideal conditions for growing a variety of grapes, especially those used in wine production. California is the leading wine-producing state in the U.S., responsible for over 80% of the country's wine output, with regions like Napa Valley and Sonoma Valley being particularly famous.

In addition to winemaking, California also produces table grapes, which are enjoyed both domestically and internationally. The state's long growing season allows for a significant harvest, further solidifying its reputation in grape cultivation.

While wheat, olives, and cotton are also grown in the state, they do not have the same extensive impact on the agricultural identity of California as grapes do. The prominence of grapes, particularly in the form of wine, makes this answer the most appropriate choice.