题目内容：
According to the last two paragraphs，what did the previous researchers think about the hu—man eye’s light—sensing system?
A．The human eye had two light—sensing systems． B．The human eye had one light—sensing system．
C．The human eye could sense the light of day more quickly than the dark of night．
D．The human eye could reset our internal clocks in accordance with the alarm clocks．
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答案解析：