A research team conducted a study involving $800$ participants, randomly selected from a specific demographic group, to investigate the correlation between Factor X and Outcome Y. The study found a strong positive correlation, with a correlation coefficient of $0.85$. Based on this finding, which of the following statements must be true?

I. For all individuals in this demographic group, an increase in Factor X directly causes an increase in Outcome Y.
II. If the study were repeated with a different group of $800$ randomly selected participants from the same demographic, the correlation coefficient would be exactly $0.85$.
III. The observed correlation of $0.85$ implies that there are no other factors influencing Outcome Y for individuals in this demographic.