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

Example Input: What is formed when nitrogen and sulfur oxides dissolve in rain?
Example Output: acid rain

Example Input: What type of organism is commonly used in preparation of foods such as cheese and yogurt?
Example Output: mesophilic organisms

Example Input: The great astronomer edwin hubble discovered that all distant galaxies are receding from our milky way galaxy with velocities proportional to their what?
Example Output:
distances