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

Example Input: Clear mucus is secreted before ejaculation to neutralize acidic urine remaining in the urethra.
Example Output: What is secreted before ejaculation to neutralize acidic urine remaining in the urethra?

Example Input: The water in some springs are hot because they're heated by hot magma.
Example Output: The water in some springs are hot because they're heated by what?

Example Input: Trees release oxygen gas as a byproduct of photosynthesis, thereby facilitating human respiration.
Example Output:
Trees release what gas as a byproduct of photosynthesis, thereby facilitating human respiration?