user: Question: What's the Representative listed that has a Presentation of Credentials of August 25, 1851?
Columns: ['Representative', 'Title', 'Presentation of Credentials', 'Termination of Mission', 'Appointed by']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Robert B. McAfee', "Chargé d'Affaires", 'July 1, 1833', 'June 20, 1837', 'Andrew Jackson']
SQL:

assistant: SELECT "Representative" FROM "Table" WHERE "Presentation of Credentials" = 'August 25, 1851';