SELECT T1.treatment_type_description FROM Treatment_types AS T1 JOIN Treatments AS T2 ON T1.treatment_type_code  =  T2.treatment_type_code GROUP BY T1.treatment_type_code ORDER BY sum(cost_of_treatment) ASC LIMIT 1
Give me the description of the treatment type whose total cost is the lowest.
SELECT T1.treatment_type_description FROM Treatment_types AS T1 JOIN Treatments AS T2 ON T1.treatment_type_code = T2.treatment_type_code GROUP BY T1.treatment_type_code ORDER BY sum ( cost_of_treatment ) ASC LIMIT 1
select t1 . treatment_type_description from treatment_types as t1 join treatments as t2 on t1 . treatment_type_code = t2 . treatment_type_code group by t1 . treatment_type_code order by sum ( cost_of_treatment ) asc limit value
Give me the description of the treatment type whose total cost is the lowest .