S1 introduces the subject of the paragraph, the Renaissance. R follows S1 as it talks about the beginnings of the Renaissance. Q follows R as ‘began in northern Italy and then spread through Europe’ in R links with ‘When the Italian cities traded with the Arabs’ in Q. P follows Q as ‘these ideas’ in P refers to ‘the ideas that were exchanged along with goods’ in Q. Thus, the correct sequence is RQP.