Children born in Japan today can expect to live five years longer than their American counterparts. Life expectancy has been rising in all countries, but the slowest rate of increase has been in the USA. What could account for this, given that the percentage of people who smoke is roughly the same in all rich countries? Of course, the USA is the birthplace of fast food restaurants that sell unhealthy food. Moreover, a recent survey of American lifestyles has found that overeating and failure to exercise are widespread amongst the population. So we must assume that obesity and lack of exercise have caused the USA to lag behind in the increase in life expectancy.
Which one of the following, if true, most weakens the above argument?
A. Most rich countries have the same standard of medical expertise.
B. The USA spends more money on fast food than any other nation.
C. Japanese children had a healthier diet in the 1960s than they do today.
D. In the 1960s and 1970s the USA had the highest percentage of smokers.
E. American fast food restaurants are now found in most rich countries.