In the Bay Area, what is the most common type of food served by restaurants?
the Bay Area refers to region = 'bay area'; the most common type of food refers to max(count(food_type))
SELECT T2.food_type FROM geographic AS T1 INNER JOIN generalinfo AS T2 ON T1.city = T2.city WHERE T1.region = 'bay area' GROUP BY T2.food_type ORDER BY COUNT(T2.food_type) DESC LIMIT 1