根据以下材料，回答36-40题
Skyrocketing tuition fees have made the headlines, leaving many wondering whether college is moving out of reach of the middle class. But while costs have indeed risen, such stories tend to exaggerate the magnitude of the increase by citing the published or "sticker" cost of college, rather than the actual cost. Since 1990 the sticker prices of public and private colleges have increased 104% and 67% respectively. But once scholarships and grants are added in, those numbers drop to 72% and 24%.
Why the discrepancy? Part of the reason is an increased practice of price discrimination, economic jargon for the act of charging some customers more than others for the same product based on their willingness to pay. Colleges are exceptionally good price discriminators because they have perfect knowledge of their applicants' finances. Students seeking financial aid must fill out a form disclosing both their family's income and finances. That information, along with an applicant's academic records allow universities to gauge a student's outside option and form a decent estimate of how much they are willing to cough up. Setting a high sticker price conveniently forces more applicants to reveal their finances.
Rich students care less about the price, and colleges may be happy to take their money provided that students pass a minimum standard of academic achievement. For everyone else, the economics get complicated. Just as there is a limited number of spots at top universities, there are a limited number of brilliant applicants. In order to keep up academic standards, colleges have to be willing to "bid" on applicants with scholarships. The game theory behind the university admissions is fascinating to observers, but maddening for students trying to decide on a college.
Two years ago President Obama proposed that the federal government create its own college ranking system to provide some clarity to applicants. Producing any sort of fair and comprehensive rankings system was always going to be difficult and the education establishment was predictably critical. On September 12, the Obama administration revealed that it had scaled its ambition right back by launching a "college scorecard", which instead of assigning a grade to colleges, merely allowed prospective students to compare colleges by three factors: graduation rate, average annual cost of attendance and median earnings of alumni.
All private colleges have roughly the same sticker price, but net prices vary significantly. For the richest students, more selective schools tend to cost more, while for low and middle-income students, just the opposite is true. On average, less selective universities tend to have very little in the form of investment income. Instead, in order to attract bright students from lower-families, they must rely on rich students to subsidize the poor.
This is admirable, but it also has the effect of driving up tuition.A recent paper from the University of Chicago shows that while price discrimination does help poorer students, 70% of the benefits went to the universities themselves. Worse yet, higher sticker prices discourage poorer students from applying to prestigious universities. Mr.Obama's college scorecard doesn't begin to answer the riddle of college finances.
Why do colleges usually set a high sticker price?

A To appeal to applicants with better academic records.

B For an easier evaluation of students' readiness to pay.

C To select applicants in need of economic assistance.

D For forming a more effective scholarship distributing system.