Which of the following statements are valid summaries of key ideas in our discussion of observational studies and experiments? (1) We can use information from an observational study to test a claim about a population. [ Select ] (2) We can use information from an observational study to establish an association between two variables. [ Select ] (3) We can use information from observational studies to prove a cause-and-effect relationship exists between two variables. [ Select ] (4) We should be cautious about the use of information from observational studies as evidence of a cause-and-effect relationship. [ Select ] (5) Observational studies that together meet specific criteria can provide some evidence for a cause-and-effect relationship. But a well-designed experiment is the only legitimate way to establish a cause-and-effect relationship. [ Select ]