An inference question about a study tests what its results let you conclude. When researchers vary two factors, compare one factor at a time while holding the other fixed. Write what changed in each pair, because an effect in one setting doesn't prove the same effect in another. Then predict without going beyond the results, keeping every setting tied to its result and checking whether any separate observations agree. Wrong choices often stretch what a result can show beyond the settings tested.
Hints
- Hint 1
The study uses four combinations of daylight and night temperature. Compare pairs that differ in only one of those factors.
- Hint 2
Compare warm and cool nights at each daylight length separately. What does changing night temperature do in each pair?
- Hint 3
For the field dataset, check when the temperature link appears. Does that timing agree with the controlled study?
Step-by-step
Compare one factor at a time
Step 1Find what short daylight does
The researchers varied daylight length and night temperature across four regimes, so the conclusion must fit every combination. What happens when days get shorter while night temperature stays fixed? Short daylight advanced coloration under both night temperatures means that short days advanced color even with warm nights. Cool nights aren't needed for the daylight effect.
- Step 2
Test the temperature effect
Now reverse the comparison: what changes when nights get cooler while daylight stays fixed? Cooling gave an additional advance under short daylight but no measurable change under long daylight. The extra advance with short days is a temperature effect, since daylight stayed fixed in that pair. With long days, cooling added no measurable advance, so the measured temperature effect depends on daylight length. That doesn't show cooling can advance color on its own.
- Step 3
Check the field result
In the field, cool nights predicted earlier color only after daylight had fallen below 12 hours. Does that fit the experiment? It does, because the temperature link again appeared with shorter days, so the field result backs the link to shorter days.
- Step 4
Choose the conclusion that keeps the limits
Which conclusion stays within these results? An independent trigger would give cooling an effect under long days, which the experiment didn't find. The words cool nights are required miss the short-day advance with warm nights, while due entirely to the seasonal shortening of days ignores cooling's added effect at fixed daylight. The wording appears to establish a condition fits because cooling's added effect appears in the short-day setting. Choice B.