user: Question: What was the reason for change to the successor that was seated on December 13, 1880?
Columns: ['District', 'Vacator', 'Reason for change', 'Successor', 'Date successor seated']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Iowa 5th', 'Rush Clark (R)', 'Died April 29, 1879', 'William G. Thompson (R)', 'October 14, 1879']
SQL:

assistant: SELECT "Reason for change" FROM "Table" WHERE "Date successor seated" = 'December 13, 1880';