What is the passage mainly about?

Câu hỏi: Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions from 35 to 42
For most of human history, the majority of the world's population struggled to get enough food. Although starvation is also a big issue in some countries, many nations are now facing the opposite problem - people are consuming too much food. In the past few decades, obesity has become a global concern that physicians around the globe are trying to deal with.
Obesity occurs when a person becomes so overweight that their extra weight starts to endanger their health. Many experts believe that the rise of obesity is closely linked to the rise of cheap, high-calorie foods that bring little health benefits. These foods often contain lots of salt, sugar, and fat. But this is not the only reason that people are getting heavier. In addition to poor food choices, people are burning fewer calories because their lives have become lazier and they don't get enough exercise.
There is no denying that the statics are alarming. Since 1980, the world's obesity rate has almost doubled. Furthermore, the number of obese people is roughly about equal to the number of people who are underweight. This increasing obesity rate has led to skyrocketing health care costs in several countries. Obesity has been shown to increase the risks of several deadly diseases. This includes heart disease, some forms of cancer, and diabetes.
Dealing with obesity has proven to be more difficult than originally anticipated. This is because there are many factors which contribute to people becoming obese. First, if you walk through any supermarket, you will find many more processed foods than fresh ones like fruits and vegetables. Although these processed foods are void of nutrition, they are much cheaper and easier to prepare than fresh foods. Corporate marketing campaigns make things worse, as companies that sell junk foods will spend millions of dollars to convince consumers to buy their foods without mentioning that they are unhealthy.
Some people are fighting back obesity though, including the former US First Lady Michelle Obama. She has started an organization called Let's Move that specifically targets childhood obesity. The organization believes in educating students, parents, and educators about how to prepare healthy foods and showing them fun ways to get exercise. Let's Move also works closely with schools to ensure that nutritious and affordable meals are provided in schools, so the process of staying in shape won't be difficult. Although we are a long way from defeating the obesity problem, programs like this one are a good start.
What is the passage mainly about?
A. Some different programs started by Michelle Obama.
B. The types of foods people should eat to get skinny
C. Jobs that are making people's lives more difficult.
D. A health issue facing many nations around the globe