Correct option is A
Analyzing Conclusion I:
The statement explicitly suggests that eight hours of sleep improves marks by 20% compared to six hours.
Therefore,
Conclusion I logically follows because the research directly supports the idea that eight hours of sleep is better for improving marks.
Analyzing Conclusion II:
The statement does not mention stress or difficulty level of exams.
While exams can be stressful, the given statement provides no evidence to conclude that students are stressed because exams are tough.