user: Question: What's the production code of the episode originally aired on February 21, 1985?
Columns: ['No. in series', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code']
Types: ['real', 'text', 'text', 'text', 'text', 'real']
Sample row: [1.0, '" Pilot " "Theo\'s Economic Lesson"', 'Jay Sandrich', 'Ed. Weinberger and Michael Leeson', 'September 20, 1984', 101.0]
SQL:

assistant: SELECT "Production code" FROM "Table" WHERE "Original air date" = 'February 21, 1985';