A、It has not been found out yet. B、Because they shoulder fewer burdens. C、Because they have a good state of mind. D、Because they

Old age may not sound exciting. But recent findings offer good news for older people and for people worried about getting older. Researchers found that people become happier and experience less worry after they reach the age of 50. In fact, they say by the age of 85, people are happier with their life than they were 18 years old. The findings came from a survey of more than 340 000 adults in the United States. 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 22 and 25. The findings showed that stress levels dropped sharply after people reached their 50s.(16)Happiness was highest among the youngest adults and those in their early 70s. The people least likely to report feeling negative emotions were those in their 70s and 80s. (17)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. The findings appeared in the Proceedings of the National Academy of Sciences. (18)Researchers say they do not know why happiness increases as people get older. One theory proposed by some sociologists 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.
16. What does the speaker say about the recent findings?
17. What can be inferred about happiness from the passage?
18. According to the researchers, why do people become happier when they get older?