Question

一道托福阅读题，着急啊，高分悬赏在线等！

Paragraph 2：When crayfish are kept continuously in the dark, even for four to five months, their compound eyes continue to adjust on a daily schedule for daytime and nighttime vision. Horseshoe crabs kept in the dark continuously for a year were found to maintain a persistent rhythm of brain activity that similarly adapts their eyes on a daily schedule for bright or for weak light. Like almost all daily cycles of animals deprived of environmental cues, those measured for the horseshoe crabs in these conditions were not exactly 24 hours. Such a rhythm whose period is approximately—but not exactly—a day is called circadian. For different individual horseshoe crabs, the circadian period ranged from 22.2 to 25.5 hours. A particular animal typically maintains its own characteristic cycle duration with great precision for many days. Indeed, stability of the biological clock's period is one of its major features, even when the organism's environment is subjected to considerable changes in factors, such as temperature, that would be expected to affect biological activity strongly. Further evidence for persistent internal rhythms appears when the usual external cycles are shifted—either experimentally or by rapid east-west travel over great distances. Typically, the animal's daily internally generated cycle of activity continues without change. As a result, its activities are shifted relative to the external cycle of the new environment. The disorienting effects of this mismatch between external time cues and internal schedules may persist, like our jet lag, for several days or weeks until certain cues such as the daylight/darkness cycle reset the organism's clock to synchronize with the daily rhythm of the new environment.

10. In paragraph 2, why does the author mention that the period for different horseshoe crabs ranges from 22.2 to 25.5 hours?
○ To illustrate that an animal's internal clock seldom has a 24-hour cycle
○ To argue that different horseshoe crabs will shift from daytime to nighttime vision at different times
○ To illustrate the approximate range of the circadian rhythm of all animals
○ To support the idea that external cues are the only factors affecting an animal's periodic behavior

我觉得A和C都有可能是对的，为了不影响大家，先不放答案了。在线等，急急急急急！

Answer 1

是应该选A ， Like almost all daily cycles of animals deprived of environmental cues, those measured for the horseshoe crabs in these conditions were not exactly 24 hours.（跟很多白天周期……的一样，那些夜间的也是确切的24小时，）such...（例如……），其实按照文中所说一个循环周期本来就不是正好24小时的（Such a rhythm whose period is approximately—but not exactly—a day is called circadian）

Answer 2

选A

C中的all animals 和 horseshoe crabs不符

而ranged from 22.2 to 25.5 hours也是解释前文not exactly 24 hours.

Answer 3

a