The excerpt that best develops the author's idea that there is a noticeable difference between the rich and the poor is:
(7) So passed the autumn, and the hard times came. The rich tried on the new winter fashions, and the poor shivered with the cold. It became more and more difficult for well-gloved hands to leave the warm muff or the fur-lined coat to take out a copper for the beggar, and more and more desperate became the struggle for bread amongst the problematical of the street.
This excerpt highlights the contrast between the rich, who can afford new winter fashions and luxury items like warm muffs and fur-lined coats, and the poor, who suffer in the cold and struggle to even obtain a copper coin for basic needs like food. It emphasizes the disparity in wealth and living conditions between the two groups, supporting the author's idea of a noticeable difference between the rich and the poor.