求TPO23閱讀第一篇第六題的答案 - 英檢

我是選(B)，但PPS上的答案是說(A)，之後我在網路上找說明，
發現這題有人說是(A)也有人說是(B)，想請教各位正確答案是什麼？


The burning of fuel, such as by cars, is not the only source of this increased heat. Two other factors contribute to the higher overall temperature in cities. The first is the heat capacity of the materials that constitute the city, which is typically dominated by concrete and asphalt. During the day, heat from the Sun can be conducted into these materials and stored—to be released at night. But in the countryside materials have a significantly lower heat capacity because a vegetative blanket prevents
heat from easily flowing into and out of the ground. The second factor is that radiant heat coming into the city from the Sun is trapped in two ways: (1) by a continuing series of reflections among the numerous vertical surfaces that buildings present and (2) by the dust dome the cloudlike layer of polluted air that most cities produce. Shortwave radiation from the Sun passes through the pollution dome more easily than outgoing longwave radiation does; the latter is absorbed by the gaseous pollutants of
the dome and reradiated back to the urban surface.

6. How is paragraph 3 organized?
(A)It describes two factors that contribute to the increased heat of cities and then provides two causes for the second factor.
(B)It describes two causes discovered in an early analysis of the increased heat of cities.
(C)It describes two factors that contribute to the increased heat of cities and two other factors that work again it.
(D)It describes two well-established caused of the increase heat of cities and other two whose roles are less well understood.




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