user: Question: Which U15 4th Quad had a U15 3rd Quad of BBC and U15 6th Quad of GT?
Columns: ['Crew', 'Open 1st VIII', 'Open 2nd VIII', 'Open 3rd VIII', 'U16 1st VIII', 'U16 2nd VIII', 'U16 3rd VIII', 'U15 1st Quad', 'U15 2nd Quad', 'U15 3rd Quad', 'U15 4th Quad', 'U15 5th Quad', 'U15 6th Quad']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [2003.0, 'NC', 'ACGS', 'BBC', 'ACGS', 'BBC', 'BBC', 'ACGS', 'ACGS', 'BBC', 'GT', 'BBC', 'GT']
SQL:

assistant: SELECT "U15 4th Quad" FROM "Table" WHERE "U15 3rd Quad" = 'BBC' AND "U15 6th Quad" = 'GT';