The list shown here includes bit in the list of "exact numeric types".
http://msdn.microsoft.com/en-us/library/ms187752.aspx (Data Types (Transact-SQL))
The definition of bit, shown here, calls it "An integer data type that can take a value of 1, 0, or NULL."
http://msdn.microsoft.com/en-us/library/ms177603.aspx (bit (Transact-SQL))
- a bit can only store 0 and 1, so it is an "exact number integer data type", as specified in the question
- bit doesn't support negative numbers
- 0-1 is a smaller range than 0-255
The correct answer should be bit.