Given a scientific passage and an answer, generate a question for the given answer.

[EX Q]: Passage: If a solute is a solid or liquid, increasing the temperature increases its solubility. For example, more sugar can dissolve in hot water than in cold water. Answer: increases its solubility
[EX A]: What does increasing a solute's temperature do?

[EX Q]: Passage: Producers are living things that use energy to make food. Producers make food for themselves and other living things. There are two types of producers:. Answer: producers
[EX A]: Living things that use energy to make food, both for themselves and other living things, are what part of an ecosystem?

[EX Q]: Passage: Investigation is at the heart of science. It is how scientists do research. Scientific investigations produce evidence that helps answer questions and solve problems. If the evidence cannot provide answers or solutions, it may still be useful. It may lead to new questions or problems for investigation. As more knowledge is discovered, science advances. Answer: investigation
[EX A]:
In science, what process produces evidence that helps answer questions and solve problems?