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

Example Input: When the smooth muscle relaxes, the arterioles dilate, allowing blood to enter the capillaries.
Example Output: When the smooth muscle relaxes, the arterioles dilate, allowing blood to enter the what?

Example Input: Invertebrates (and higher animals) can also be placed in one of two groups based on how they develop as embryos.
Example Output: Invertebrates (and higher animals) can also be placed in one of two groups based on how they develop as what?

Example Input: Salicylic acid do willow trees produce to kill bacteria.
Example Output:
What do willow trees produce to kill bacteria?