【单选题】

Passage TwoPeople are living longer than ever, but for some reason, women are living longer than men.

A、baby boy born in the United States in 2003 can expect to live to be about 73, a baby girl, about 79. This is indeed a wide gap, and no one really knows why it exists. The greater longevity (长寿) of women, however, has been known for centuries. It was, for example, described in the seventeenth century. However, the difference was smaller then—the gap is growing.
A、number of reasons have been proposed to account for the differences. The gap is greatest in industrialized societies, so it has been suggested that women are less susceptible to work strains that may raise the risk of heart disease and alcoholism. Sociologists also tell us that women are encouraged to be Jess adventurous than men (and this may be why they are more careful drivers, involved in fewer accidents). Even smoking has been implicated in the age discrepancy. It was once suggested that working women are more likely to smoke and as more women entered the work force, the age gap would begin to close, because smoking is related to earlier deaths. Now, however, we see more women smoking and they still tend to live longer although their lung cancer rate is climbing sharply.One puzzling aspect of the problem is that women do not appear to be as healthy as men. That is, they report far more illnesses.But when a man reports an illness, it is more likely to be serious.Some researchers have suggested that men may die earlier because their health is more strongly related to their emotions. For example, men tend to die sooner after losing a spouse than women do. Men even seem to be more weakened by loss of a joB、Both of these are linked with a marked decrease in the effectiveness of the immune system).Among men, death follows retirement with an alarming promptness.Perhaps we are searching for the answers too close to the surface or the problem. Perhaps the answers lie deeper in our biological heritage.After all, the phenomenon is not isolated to humans. Females have the edge among virtually all mammalian (哺乳动物) species, in that they generally live longer. Furthermore, in many of these species the differences begin at the moment of conception; there are more male miscarriages (流产). In humans, after birth, more baby boys than girls die.What can we learn from the first two paragraphs
A、Men’s lifespan remains almost unchangeD、
B．Researchers have found the causes of the age gap.
C．The more advanced a society, the greater the age gap.
D．The age gap was noticed only recently.