what are all the gtc winners for pole position no. 21 team modena
CREATE TABLE table_17973 (
    "Round" real,
    "Circuit" text,
    "Date" text,
    "Length" text,
    "Pole Position" text,
    "GT3 Winner" text,
    "GTC Winner" text
)
SELECT "GTC Winner" FROM table_17973 WHERE "Pole Position" = 'No. 21 Team Modena'
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 are all the gtc winners for pole position no. 21 team modena ### Input: CREATE TABLE table_17973 (
    "Round" real,
    "Circuit" text,
    "Date" text,
    "Length" text,
    "Pole Position" text,
    "GT3 Winner" text,
    "GTC Winner" text
) ### Response: SELECT "GTC Winner" FROM table_17973 WHERE "Pole Position" = 'No. 21 Team Modena'