Teacher:Given a scientific passage and an answer, generate a question for the given answer.
Teacher: Now, understand the problem? Solve this instance: Passage: A type of lipid called trans fat is found in many processed foods. Trans fat is rare in nature but is manufactured and added to foods to preserve freshness. Eating foods that contain trans fat increases the risk of heart disease. Trans fat may be found in such foods as cookies, doughnuts, crackers, fried foods, ground beef, and margarine. Answer: trans fat
Student:
What is manufactured and added to foods to preserve freshness?