Which of the following statements is NOT true? A) We can use results from an observational study to test a claim about a population. O B) We can use results from an observational study to establish an association between two variables. O C) When many observational studies together met specific criteria, the results can provide varying degrees of evidence for a cause-and-effect relationship between two variables. But we should be cautious in interpreting such results. O D) When an observational study has a large sample and follows people for many years, we can use the results to establish a cause-and-effect relationship between two variables. O E) A well-designed experiment is the most certain method to establish a cause-and-effect relationship between two variables