Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_30 (player VARCHAR, transfer_fee VARCHAR, pos VARCHAR)
### Question:
Who had a transfer fee of released and played the position of DF?
### Answer:
SELECT player FROM table_name_30 WHERE transfer_fee = "released" AND pos = "df"