In contrast, if a factory makes clothes alone (30 days a month), it makes 45 pieces a day and 90 pairs of pants a day; Factory B makes 200/3 clothes and 80 pairs of pants every day. It is found that factory B has stronger production capacity and higher efficiency in making clothes. Factory B makes clothes, and factory A makes pants alone. Factory B produces 200/3 * 30 = 2,000 pieces of clothes a month, while factory A produces 90 * 30 = 2,700 pairs of pants. In order to match, a factory only needs to produce 2000 pairs of pants, which takes 22.22 days, and the rest of the time to make complete sets of clothes and pants, which can be 7.78*30=233 sets. In the end, the total is 2000+233=2233 sets, so choose D.