Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Problem:Passage: Glutathione is a low-molecular-weight compound found in living cells that is produced naturally by the liver. Healthcare providers give glutathione intravenously to prevent side effects of chemotherapy and to prevent kidney problems. Answer: liver
Solution:
Glutathione is a low-molecular-weight compound found in living cells that is produced naturally by what?