How many transactions have been made to purchase a root beer brand from California?
California refers to State = 'CA';
SELECT COUNT(T3.RootBeerID) FROM rootbeerbrand AS T1 INNER JOIN rootbeer AS T2 ON T1.BrandID = T2.BrandID INNER JOIN `transaction` AS T3 ON T2.RootBeerID = T3.RootBeerID WHERE T1.State = 'CA'