C. 10,000 feet
Argentina has vineyards planted up to 9,800 feet above sea level, which is roughly a third the height of Mt. Everest (and probably higher than most of us would be willing to hike on a normal basis). At these altitudes, hail and frost are the primary vineyard concerns, however the vines also enjoy more tempered high and low temperatures and more sunlight, which are beneficial for grape development.
Joe Roberts is the creator of the popular & award-winning website 1WineDude.com, which publishes wine reviews, interviews, & entertaining Op/Ed commentary on the wine world. He lives in Pennsylvania with his daughter Lorelai Kate. You can follow his exploits (and witty “mini” wine reviews) on twitter at twitter.com/1winedude & facebook at facebook.com/1winedude.