Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: The prostate gland secretes a fluid that mixes with sperm to help form semen. Semen is a whitish liquid that contains sperm. It passes through the urethra and out of the body. Answer: prostate gland
A:
What gland secretes a fluid that mixes with sperm to help form semen?