Q: Read the following article and answer the question. Article: Everyone wants to know the secrets of a long and healthy life. Here are some discoveries from health experts. Many studies looking into the lives of centenarians  look at what they eat. Many people who live into their hundreds live in the Mediterranean , so their diet, which is high in fruits, vegetables, nuts, and healthy fats like olive oil, gets a lot of attention. The diet has been linked to a healthier older age, lower risk for heart disease, and even protection against memory loss.  Education is related to a longer life. A 2012 report from the CDC's National Center for Health Statistics found that people with a bachelor's degree or higher live about nine years longer than people who don't graduate high school. James Smith, a health economist at the RAND Corporation, is also a supporter of the argument for staying in school for better life expectancy. His findings show education should be an even bigger factor than race and income. Educated people are more likely to land better jobs, plan for their future, and make healthier lifestyle choices. Being a hard worker doesn't necessarily mean job-stress will harm you. The Longevity Study found that plenty of hard workers lived long lives. "Skeptics  may wonder if hard workers really are enjoying life." the authors write, "We found that productive, hardworking people (even in old age) are not stressed or miserable, but tend to be happier, healthier, and more socially connected than their less productive peers." Having a strong social group is associated with a longer life. We often turn to friends and family for support, and taking care of the people that matter to us may help us take better care of ourselves, some evidence shows. Some research even suggests that immune  function is improved when we are around our friends, and that they help with stress management. Research shows that sitting for long period of time put people at risk for shorter lifespans and other health risks. A 2011 study found that each hour people spent sitting down and watching TV after... Question: The passage is mainly about   _  . Answer:

Select from the following. a. diet and health; b. the value of good education; c. some discoveries on health; d. the secret of a happy life;
The answer is:
c.