Being physically active three times a week reduces the odds of being depressed by about 16%, according to new UCL research carried out as part of the Public Health Research Center. The study, published in JAMA Psychiatry, found a two-way relationship between depression and physical activity. People who increased their weekly activity reported fewer depressive symptoms but those with more depressive symptoms were less active, particularly at younger ages. Researchers followed 11,135 people born in 1958 up until the age of 50, recording depressive symptoms and levels of physical activity at regular intervals in adulthood. They found that each additional activity period per week reduced odds of depression by 6%. In England 19% of men and 26% of women are currently classed as "inactive", and this study suggests that activity could significantly improve their mental as well as physical health. "Assuming the association is causal, physical activity has a protective effect against depression. If an adult between their twenties and forties who isn't physically active became active 3 times per week, they would reduce their risks of depression by about 16%." says Dr Snehal of the UCL Institute of Child Health, lead author of the study. Professor Mark, Director of the Public Health Research Center, said, "Many people are already aware of the benefits of physical activity on their general health, but now we are seeing more evidence that suggest it also has a positive effect on a person's mental well-being. The latest research highlights just how important it is to ensure that people are working and living in environments that allow them to be both physically active and mentally healthy." What is the author's purpose in writing the passage? A) To tell us a fun story about how to protect us against depression. B) To introduce a research on the link between activity and depression. C) To persuade readers to increase their weekly activity. D) To describe the disadvantages of physical activity.
A:
B