In two common species of flowers, A and B, the proportions of flowers that are blue are and , respectively. Suppose that independent random samples of 50 species-A flowers and 100 species-B flowers are selected. Let be the sample proportion of blue species-A flowers and be the sample proportion of blue species-B flowers. What is the mean of the sampling distribution of ? A) Pa- Pb B) Pa/50 - Pb/100 C) Pa^ - PB^ D) Pa(1-pa)/50 + Pb(1-pb)/100 E) √Pa(1-pa)/50 + Pb(1-pb)/100