Which Sleeves have a Back of Unknown?
CREATE TABLE table_44510 (
    "Year" text,
    "Supplier" text,
    "Chest" text,
    "Sleeves" text,
    "Back" text
)
SELECT "Sleeves" FROM table_44510 WHERE "Back" = 'unknown'
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: Which Sleeves have a Back of Unknown? ### Input: CREATE TABLE table_44510 (
    "Year" text,
    "Supplier" text,
    "Chest" text,
    "Sleeves" text,
    "Back" text
) ### Response: SELECT "Sleeves" FROM table_44510 WHERE "Back" = 'unknown'