Consider the following output for a one-sample procedure from R's t.test. One Sample t-test data: data t=4.1894, df = 49, p-value = 0.0001162 alternative hypothesis: true mean is not equal to 15 95 percent confidence interval: 16.61141 19.58255 sample estimates: mean of x 18.09698 Which of the following statements are true? There may be more than one correct statement; check all that are true. a) We can be 95% confident that the sample mean lies between 16.61141 and 19.58255. b) There is strong evidence that the true mean is equal to 15. c) There were 49 observations in the sample (n = 49). d) One way to express the null hypothesis used in this test isHo=15