Task: Text to Code
Input (English): Step 1: For each row in Customers_Cards table, find the corresponding rows in Financial_Transactions table.
Step 2: find the number of rows of each value of transaction_type in the results of step 1.
Step 3: find card_type_code of step 1 results with largest value in the results of step 2
Output (English): SELECT T1.card_type_code FROM Customers_Cards AS T1 JOIN Financial_Transactions AS T2 ON T1.card_id = T2.card_id GROUP BY T2.transaction_type ORDER BY Count ( * ) Desc LIMIT 1