CREATE TABLE table_name_68 (u15_4th_quad VARCHAR(255), u15_3rd_quad VARCHAR(255), u15_6th_quad VARCHAR(255))
Which U15 4th Quad had a U15 3rd Quad of BBC and U15 6th Quad of GT?
    
SQL: SELECT u15_4th_quad FROM table_name_68 WHERE u15_3rd_quad = "bbc" AND u15_6th_quad = "gt"