Aldi would like to study the effectiveness of the weekly promotions sent by direct mail to consumers. They random select 200 supermarkets across Europe and track the weekly direct mail promotions and sales for 20 weeks. Let i be the index of the supermarkets and t be the index of the weeks. They use the following model. log(Salesit) = b0i + b1iPromotionsit + b2WeekendDummyt + it b0i = m0 + m1LocalIncomei+m2LocalEducationi+zi b1i = g0 + g1LocalIncomei+g2MarketSharei+xi where LocalIncomei and LocalEducationi measure the income and education level of region where supermarket i is. MarketSharei is the market share of Aldi in that region. When this model is fitted using the R function lmer(), which of following variable is a random effect Group of answer choices Promotionsit MarketSharei LocalIncomei WeekendDummyt