题目解析：
本题为事实信息题，这道题根据4个选项的关键词我们可以快速定位。
A、B选项，通过“white light”和“sunlight”我们定位到这句话“It is evident that even
brief exposure to sunlight or white light will reset their biological clocks.”说明即使是很短的日照或白光照射都能重置它们的生物钟。因此白光和太阳光对重置生物钟有影响，故A、B选项排除。
C选项“pure red light”定位到这句话“A nighttime flash of pure red light inhibits flowering”红光会抑制开花，故红光也有影响，C选项排除。
D选项“far-red light”定位到这句“while
flash of light at the far-red end of the spectrum has no effect on flowering,
as if no light were detected.”意思是“远红光对植物开花没有影响，因为植物不会探测到光线”,所以这里，只有D选项far-red
light是植物探测不到的，所以对重置生物钟无效，故D选项正确。
Plants
seem to use the phytochrome system in combination with their internal biological clocks to detect the duration of continuous darkness. Cockleburs, for example,
flower under the schedule of sixteen hours of darkness and eight hours of light. However, interrupting the middle of the dark period with
just a minute or two of lights prevents flowering. Thus their flowering
is controlled by the length of continuous darkness. It is evident that even
brief exposure to sunlight or white light will reset their biological clocks. The color of the light used for the light exposure is also important. A nighttime flash of pure red
light inhibits flowering, while flash of light at the far-red end of the spectrum has
no effect on flowering, as if no light were detected. 
