A chemist is interested in comparing four different catalysts by measuring reaction times.Each catalyst is tested five times,with each experiment randomly assigned one of the four catalysts.

A) H0: μcat ≠ μtest vs.the alternative that catalyst and test mean times are equal
B) H0: μ1 ≠ μ2 ≠ μ3 ≠ μ4 ≠ μ5 vs.the alternative that all the test mean times are equal
C) H0: μ1 = μ2 = μ3 = μ4 vs.the alternative that not all the catalyst mean times are equal
D) H0: μ1 ≠ μ2 ≠ μ3 ≠ μ4 vs.the alternative that all the catalyst mean times are equal
E) H0: μ1 = μ2 = μ3 = μ4 = μ5 vs.the alternative that not all the test mean times are equal

The hypotheses H0: μ1 = μ2 = μ3 = μ4 versus the alternative that not all the catalyst mean times are equal is the best choice. This is because the chemist is interested in comparing the different catalysts, and wants to see if there is a difference in their mean reaction times. H0: μcat ≠ μtest (A) is not suitable because it is unclear what "cat" and "test" mean, and the chemist is interested in comparing catalysts, not tests. H0: μ1 ≠ μ2 ≠ μ3 ≠ μ4 ≠ μ5 (B) is not suitable because there are only four catalysts being tested, not five, and this hypothesis does not address the research question. H0: μ1 ≠ μ2 ≠ μ3 ≠ μ4 (D) is not suitable because it does not address whether all the catalysts have the same mean reaction time or not. H0: μ1 = μ2 = μ3 = μ4 = μ5 (E) is not suitable because it assumes that all the test mean times are equal, which is not what the chemist is trying to test.