A study finds a correlation coefficient of 0.78 between hours of sleep and productivity levels. What can be concluded about the relationship?

• A. There is a moderate negative correlation, suggesting more sleep is associated with lower productivity.
• B. There is a weak negative correlation, suggesting more sleep is associated with lower productivity.
• C. There is a strong positive correlation, suggesting more sleep is associated with higher productivity.
• D. There is no correlation between sleep and productivity.