Read the following article and answer the question. Article: Researchers found that people become happier and experience less worry after they reach the age of fifty. In fact, they say by the age of eighty-five, people are happier with their life than they were when they were eighteen years old. The findings came from a survey of more than three hundred forty thousand adults in the United States. The Gallup Organization questioned them by telephone in two thousand eight. At that time, the people were between the ages of eighteen and eighty-five. The researchers asked questions about emotions like happiness, sadness and worry. They also asked about mental or emotional stress. Arthur Stone in the Department of Psychiatry and Behavioral Science at Stony Brook University in New York led the study. His team found that levels of stress were highest among adults between the ages of twenty-two and twenty-five. The findings showed that stress levels dropped sharply after people reached their fifties. Happiness was highest among the youngest adults and those in their early seventies. The people least likely to report feeling negative emotions were those in their seventies and eighties. The findings appeared in the Proceedings of the National Academy of Sciences. Researchers say they do not know why happiness increases as people get older. One theory is that, as people grow older, they grow more thankful for what they have and have better control of their emotions. They also spend less time thinking about bad experiences. Professor Stone says the emotional patterns could be linked to changes in how people see the world, or maybe even changes in brain chemistry. The researchers also considered possible influences like having young children, being unemployed or being single. But they found that influences like these did not affect the levels of happiness and well-being related to age. The study also showed that men and women have similar emotional patterns as they grow older. However, women at all ages reported more sadness, stress and worry than men. Question: What do you think the Proceedings of the National Academy of Sciences is? Answer:

Choose from: [i] A Gallup organization.; [ii] A university in New York.; [iii] A popular science magazine.; [iv] A research institution;
The answer is:
[iii]