Which AVA is located at the northernmost part of the county with vineyards at an elevation of 200-800 feet?

The Santa Ynez Valley American Viticultural Area (AVA) is characterized by its positioning in the northern part of Santa Barbara County and is well-known for its varied elevations that typically range from 200 to 800 feet. This elevation range offers a unique microclimate that supports the cultivation of various grape varieties, contributing to the AVA's reputation for high-quality wine production.

In contrast, other regions listed, such as Santa Barbara Valley, Monterey, and Santa Lucia Highlands, have distinct geographic and climatic characteristics. For instance, while the Santa Lucia Highlands does have vineyards at higher elevations, it is more recognized for its slopes and is not the northernmost AVA in the county. Similarly, Santa Barbara and Monterey AVAs have their own unique attributes but do not meet the specific criteria regarding elevation and location described in the question. Overall, the elevation and location of the Santa Ynez Valley make it the correct choice for this question.