A study was conducted on the effects of divorce. Researchers gathered data from a random sample of 5,125 adults and measured quite a few variables, in addition to the explanatory variable of divorce and the response variable of shorter life span. According to a newspaper article summarizing the study, those who divorced were more likely to be less physically active, at an unhealthy weight, and smokers. Those who were married were about 15% more likely to be deceased. What conclusion can we draw from this study?(5 points)

• We can infer a cause-and-effect relationship because the sample was selected randomly.
• We cannot infer a cause-and-effect relationship because we do not have a control group.
• We can infer a cause-and-effect relationship because multiple variables were included.
• We cannot infer a cause-and-effect relationship because the treatments imposed were not blocked correctly.
• We cannot infer a cause-and-effect relationship because treatments were not assigned randomly.

I saw that the right answer is supposed to be E.)We cannot infer a cause-and-effect relationship because treatments were not assigned randomly. But I don't understand why this is the right answer. Can someone explain to me why this is right?