Given a scientific question, generate a correct answer to it.

Example Input: What states that chemical reactions occur when atoms, ions, or molecules collide?
Example Output: collision theory

Example Input: The short length of what in women is the best explanation for the greater incidence of uti in women?
Example Output: urethra

Example Input: Gall bladder removal surgery does not seriously affect digestion because ______ is still being produced.
Example Output:
bile