Researchers have found that people who regularly consume moderate amounts of dark chocolate exhibit lower blood pressure compared to those who do not consume dark chocolate at all. This finding suggests that including dark chocolate in one's diet may contribute to better cardiovascular health.
However, some health experts caution that this study does not consider other lifestyle factors such as diet and exercise that could also influence blood pressure. Therefore, the potential benefits of dark chocolate should not be overestimated.
Which of the following, if true, would most strengthen the argument that dark chocolate contributes to lower blood pressure?