Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: Ulcers are sores in the lining of the stomach or duodenum that are usually caused by bacterial infections. They may also be caused by the acidic environment of the stomach. Stomach acids may damage the lining of the stomach. Symptoms typically include abdominal pain and bleeding. You can see how stomach ulcers develop at this link: http://www. youtube. com/watch?v=4bXZRgJ-1fk . Answer: ulcers
A:
What are sores in the lining of the stomach or duodenum that are usually caused by bacterial infections or acidity?