prep 180 代词指代

Noting that the FederalReserve had raised a key short-term interest rate again last month, analystssaid that they expected orders for durable goods to decline soon because risinginterest rates makes it more expensive to buy them on credit
A. rising interest rates makes it more expensive to buy them on credit
B. rising interest rates make buying on credit more expensive
C. a rise in interest rates make it more expensive to buy on credit
D. a rise in interest rates make buying on credit more expensive (B)
E. a rise in interest rates makes it more expensive forthem to be bought on credit

A选项语法笔记给出的解释是：make it more expensive tobuy them中them无所指，语法上指代orders，但逻辑上应该指代durablegoods
1不懂为什么语法上会指代orders啊？看句义就晓得应该指goods啊~而且goods算就近指代啊~是因为durable goods在介词短语里才不被指代嚒？~
2到底什么时候会指代不清呢？是只要前面有两个复数名词就算指代不清嚒？
3关于them they these指代好混乱啊，到底是就近指代还是符合语义嘞？求NN解救啊啊~~~