Choose the correct answer below. A. It is necessary to assume that the populations from which you are sampling have equal population means and positive standard deviations. B. It is necessary to assume that the populations from which you are sampling have independent normal distributions and equal variances. C. It is necessary to assume that the populations from which you are sampling have unequal variances and equal sizes. D. It is necessary to assume that the populations from which you are sampling have negative t Subscript STATtSTAT test statistics and unequal sample means.