Vaillant's research showed that at age 50, the best predictors of who would be dead at 75 to 80 years of age were: chronic depression and cardiovascular disease. diabetes and depression. alcohol abuse and smoking. smoking and obesity.

The correct answer to the question: Vaillant´s research showed that at the age of 50, the best predictors of who would be dead at 75 to 80 years of age were:, would be: Alcohol abuse and smoking.

Explanation:

George Vaillant is a psychiatrist who works at Harvard Medical School and has been participant in the gran research project from that school called "Adult Development". One of the purposes of this research project was to measure different aspects that impacted happiness and well-being in people who had been, or were, related to Harvard. Through the study, several results were found, but one that was truly underlined by Vaillant when he was the one heading it, was, that the true key to a long life, and wellbeing, was the presence of good relationships, and that alcohol abuse, as well as smoking were likelier to become main reasons for people having a shorter life span than anything else.