Iven the sample information below, what test statistic should be used to determine whether the standard deviations are equal for two populations, prior to performing a hypothesis test for the equality of the population means? a. f = 1.58, with numerator degrees of freedom = 19 and denominator degrees of freedom = 29 b. f = 0.40, with degrees of freedom = 19 c. f = 2.49, with numerator degrees of freedom = 29 and denominator degrees of freedom = 19 d. t = 18.75, with degrees of freedom = 19