Câu hỏi:

Read the following passage and mark the letter A, B, Cor D to indicate the correct word or phrase that best fits each of the numbered blanks from 18 to 22.

Scientists and doctors say that about 55 million Americans are too fat. Why is this? One (18) ________ is the kind of food Americans eat. Many Americans like "fast foods". These foods (such as hamburgers and ice-cream) often have fattening things in them. (19) ________ cause is the way Americans eat. They often eat little snacks between regular meals. These extra foods (20) ________ extra fat on the body. A third cause is that they do not take enough exercise. Americans like driving everywhere instead of walking. They often have (21) ________ to do a lot of the work for them. Some Americans are also too heavy (22) ________ health problems. But for most of those 55 million people, the problem is the American lifestyle.                

Why is this? One (18) ________ is the kind of food Americans eat