CREATE TABLE table_3007 ("District" TEXT, "Vacator" TEXT, "Reason for change" TEXT, "Successor" TEXT, "Date successor seated" TEXT)

What was the reason for change when the successor was William Milnes, Jr. (C)?
SELECT "Reason for change" FROM table_3007 WHERE "Successor" = 'William Milnes, Jr. (C)'
SELECT "Reason for change" FROM "table_3007" WHERE "Successor" = 'William Milnes, Jr. (C)'