The null hypothesis in this case is Select an answer which claims that pregnancy length Select an answer related to (or affected by) whether or not the woman smokes during pregnancy. The alternative hypothesis in this case is Select an answer which claims that pregnancy length Select an answer related to (or affected by) whether or not the woman smokes during pregnancy. Note that "mu" stands for the Greek letter , the population meanmu1 stands for the mean of population 1 and mu2 stands for the mean of population 2