Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Example Input: The main advantage of urea is its very low toxicity.
Example Output: The main advantage of urea is its very low what?

Example Input: The majority of human genes have two or more possible alleles.
Example Output: How many possible alleles do the majority of human genes have?

Example Input: Thousands many pathogens can each droplet contain.
Example Output:
How many pathogens can each droplet contain?