Among the molecules with element Calcium, are they mostly carcinogenic or non carcinogenic?
calcium refers to element = 'ca'; label = '+' mean molecules are carcinogenic; label = '-' means molecules are non-carcinogenic; MAX(label)
SELECT T2.label FROM atom AS T1 INNER JOIN molecule AS T2 ON T1.molecule_id = T2.molecule_id WHERE T1.element = 'ca' GROUP BY T2.label ORDER BY COUNT(T2.label) DESC LIMIT 1