（10分）材料：美国自诩为自由市场经济，一直强调风险自负的投资原则：相对于给资信条件较好的按揭贷款人所能获得的比较优惠的利率和还款方式，次级按揭贷款人在利率和还款方式，通常要被迫支付更高的利率．并遵守更严格的还款方式。这个本来很自然的问题，却由于美国过去的6．7年来信贷宽松．金融创新活跃．房地产和证券市场价格上涨的影响，没有得到真正的实施。这样一来，次级按揭贷款的还款风险就由潜在变成现实。在这过程中，美国有的金融机构为一己之利，纵容次贷的过度扩张，最终引发了全球的金融危机。

请分析材料所反映出的经济学道理。（10分）

A proven method for effective textbook reading is the SQ3R method developed by Francis Robinson. The first step is to survey (the S step) the chapter by reading the title, introduction, section headings, summary and by studying any graphs, tables, illustrations or charts. The purpose of this step is to get an overview of the chapter so that you will know before you read what it will be about. In the second step (the Q step), for each section you ask yourself questions such as "What do I already know about this topic" and "What do I want to know" In this step you also take the section heading and turn it into a question. This step gives you a purpose for reading the section. The third step (the first of the 3 R’s) is to read to find the answer to your questions. Then at the end of each section, before going on to the next section, you recite (the second of the 3 R’s) the answers to the questions that you formed in the question step. When you recite you should say the information you want to learn out loud in your own words. The fifth step is done after you have completed steps 2, 3 and 4 for each section. You review (the last of the 3 R’s) the entire chapter. The review is done much as the survey was in the first step. As you review, hold a mental conversation with yourself as you recite the information you selected as important to learn. The mental conversation could take the form of asking and answering the questions fromed from the headings or reading the summary, which lists the main ideas in the chapter, and trying to fill in the details for each main idea.

The SQ3R method consists of（）steps.

A. three

B. four

C. five

D. seven