Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/ or increased health problems. Body mass index (BMI), a measurement which compares weight and height, defines people as overweight (pre-obese) when their BMI is between 25 kg/m2 and 30 kg/m2 , and obese when it is greater than 30 kg/m2 . Obesity increases the likelihood of various diseases, particularly heart disease, type 2 diabetes, breathing difficulties during sleep, certain types of cancer, and osteoarthritis. Obesity is most commonly caused by a combination of excessive dietary calories, lack of physical activity, and genetic susceptability although a few cases are caused primarily by genes, endocrine disorders, mediations or psychiatric illness. Evidence to support the view that some obese people have a greater energy expenditure than their thin counter parts due to the energy required to maintain an increased body mass. The primary treatment for obesity is dieting and physical exercise. To supplement this, or in case of failure, anti-obesity drugs may be taken to reduce appetite or inhibit fat absorption. In severe cases, surgery is performed or an intra-gastric balloon is placed to reduce stomach volume and/ or bowel length, leading to earlier satiation and reduced ability to absorb nutrients from food. Obesity is a leading preventable cause of death worldwide, with increasing prevalence in adult and children, and authorities view it as one of the most serious public health problems of the 21st century. Obesity is stigmatized in much of the modern world (particularly in the Western world), though it was widely perceived as a symbol of wealth and fertility at other times in history, and still is in some parts of the world. (Adapted from:http://www.myenglishpages.com/site_php_files/reading_obesity.php) What is the best summary of the passage? A. Obesity that is the main preventable cause of death can cause various diseases. Dieting and physical excercise can prevent obesity. B. Obese people tend to have health problems. The problems are considered as the 21s'century problems. C. Obesity leads to a shorter life because of the increased health problems. Therefore, people are advised to have a surgery. D. Obesity is widely considered as a symbol of wealth. Therefore, many people who are obese tend to be reluctant to do a diet. E. Obese people eat little but easily gain weight. Tn reduce iheir weight , they actually do a lot of physical exercise.