What is Surface, when Tournament is 'Sunderland , United Kingdom'?
CREATE TABLE table_name_4 (
    surface VARCHAR,
    tournament VARCHAR
)
SELECT surface FROM table_name_4 WHERE tournament = "sunderland , united kingdom"
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What is Surface, when Tournament is 'Sunderland , United Kingdom'? ### Input: CREATE TABLE table_name_4 (
    surface VARCHAR,
    tournament VARCHAR
) ### Response: SELECT surface FROM table_name_4 WHERE tournament = "sunderland , united kingdom"