user: Question: For the year 1975, what is Propulsion, with a Number (quantity ordered) of 4756-4788 (33 buses)?
Columns: ['Make/ Model', 'Length', 'Year', 'Numbers (Quantity Ordered)', 'Fuel Propulsion', 'Year Retired']
Types: ['text', 'text', 'real', 'text', 'text', 'text']
Sample row: ['Flxible 53096 "New Look"', "40'", 1973.0, '4701-4740 (40 buses)', 'Diesel', '1994']
SQL:

assistant: SELECT "Fuel Propulsion" FROM "Table" WHERE "Year" = 1975.0 AND "Numbers (Quantity Ordered)" = '4756-4788 (33 buses)';