​A researcher selects a sample from a population with μ = 30 and uses the sample to evaluate the effect of a treatment. After treatment, the sample has a mean of M = 32 and a variance of s2 = 6. Which of the following would definitely increase the likelihood of rejecting the null hypothesis?Question options:a.​Decrease the sample varianceb.​Increase the sample meanc.​Increase the sample sized.​All of the other options will increase the likelihood of rejecting the null hypothesis

Answer:Option b) Increase the sample meanStep-by-step explanation:Given that a researcher selects a sample from a population with μ = 30 and uses the sample to evaluate the effect of a treatment. After treatment, the sample has a mean of M = 32 and a variance of s2 = 6. This is a paired test with test statistic =mean diff/std errorMean difference would increase if sample mean increases.This would increase the test statisticOr otherwise decrease in variance will increase the test statisticOr Increase in sample size would also increase test statisticOf all these the II option is definite in increasing the  likelihood of rejecting the null hypothesis because this would definitely increase the chances of rejecting H0.Others may also have effect but not as much direct as sample mean difference.Because variance and sample size have influence only upto square root of the difference.