Using a cps-sample of 7,440 individuals, you estimate the following regression: = 20.91 - 2.61 x female where female is a binary variable that takes on the value of 1 for females and is 0 otherwise. the standard error on the coefficient on female is 0.25. the 95% confidence interval for the gender wage gap, or the amount that females earn less, is: a) [-3.10, -2.12] b) [18.30, 23.52] c) [-3.02, -2.20] d) [-1.96, -1.64]