Question: Which service id and type has the least number of participants?
SQL: SELECT T3.service_id ,  T4.Service_Type_Code FROM participants AS T1 JOIN Participants_in_Events AS T2 ON T1.Participant_ID  =  T2.Participant_ID JOIN EVENTS AS T3 ON T2.Event_ID   =  T3.Event_ID JOIN services AS T4 ON T3.service_id  =  T4.service_id GROUP BY T3.service_id ORDER BY count(*) ASC LIMIT 1