Banks often have one line serving multiple teller stations. The next person in line is helped by the next teller available. Grocery stores typically have a separate line for each clerk. Why might that be?

A、Lines must move faster in a grocery store because frozen food will melt.;

B、Banks allocate service using the first come, first served method and grocery stores allocate service using the price method.;

C、Grocery stores are more interested in efficiency, and banks are more interested in customer service.;

D、Bulky shopping carts make a single line impractical in a grocery store, but people waiting in line at the bank do not have to maneuver carts through the line.