急件！请教几个逻辑问题

TEST-2 -Q28. Ordinary mountain sickness, a common condition among mountain climbers, and one from which most people can recover, is caused by the characteristic shortage of oxygen in the atmosphere at high altitudes. Cerebral edema, a rarer disruption of blood circulation in the brain that quickly becomes life-threatening if not correctly treated from its onset, can also be caused by a shortage of oxygen. Since the symptoms of cerebral edema resemble those of ordinary mountain sickness, cerebral edema is especially dangerous at high altitudes.

Which one of the following is an assumption on which the argument depends?

(A) The treatment for ordinary mountain sickness differs from the treatment for cerebral edema.

(B) Cerebral edema can cause those who suffer from it to slip into a coma within a few hours.

(C) Unlike cerebral edema, ordinary mountain sickness involves no disruption of blood circulation in the brain.

(D) Shortage of oxygen at extremely high altitude is likely to affect thinking processes and cause errors of judgment.

(E) Most people who suffer from ordinary mountain sickness recover without any special treatment.

A 请问为什么啊？

29. The price of a full-fare coach ticket from Toronto to Dallas on Breezeway Airlines is the same today as it was a year ago, if inflation is taken into account by calculating prices in constant dollars. However, today 90 percent of the Toronto-to-Dallas coach tickets that Breezeway sells are discount tickets and only 10 percent are full-fare tickets, whereas a year ago half were discount tickets and half were full-fare tickets. Therefore, on average, people pay less today in constant dollars for a Breezeway Toronto-to-Dallas coach ticket than they did a year ago.

Which one of the following, if assumed, would allow the conclusion above to be properly drawn?

(A) A Toronto-to-Dallas full-fare coach ticket on Breezeway Airlines provides ticket-holders with a lower level of service today than such a ticket provided a year ago.

(B) A Toronto-to-Dallas discount coach ticket on Breezeway Airlines costs about the same in constant dollars as they did a year ago.

(C) All full-fare coach tickets on Breezeway Airlines cost the same in constant dollars as they did a year ago.

(D) The average number of coach passengers per flight that Breezeway Airlines carries from Toronto to Dallas today is higher than the average number per flight a year ago.

(E) The criteria that Breezeway Airlines uses for permitting passengers to buy discount coach tickets on the Toronto-to-Dallas route are different today than they were a year ago.

为什么是B呢？

我觉得应该是原价跟以前一样现在打折多才会花钱少了啊，为什么打折扣跟以前一样用的钱就少了呢？