Light exposure can help alleviate winter depression. Researchers have studied nine patients who all suffered from winter depression due to shorter winter days. Researchers exposed the patients to strong light with floral fragrance for three hours in the morning and three hours in the evening. Within a week, seven patients completely got rid of depression and the other two showed significant improvement. As the light could induce the body to mistakely think that summer is coming, winter depression was cured. Which of the following, if true, would weaken the conclusion of the above argument? ["Researchers' intentional use of floral scent, when exposed to strong light, has a significant effect on improving the indications for patients with winter depression.", 'The experiment was conducted in the temperate climate of the northern hemisphere, and the experimental differences between the northern and southern hemispheres cannot be distinguished or excluded in advance.', 'Damage to the skin from intense light has been confirmed by special studies, and summer is more harmful than winter.', "The non-working state of six hours a day changes the patients' original living environment and improves their mentality, which is a major impact on patients with depression."]