[单项选择]
Prolonging Human Life
Prolonging human life has increased the size of the human population. Many people alive today would have died of childhood diseases if they had been born 100 years ago. Because more people live longer, there are more people around at any given time. In fact, it is a decrease in death rates, not an increase in birthrates, that has led to the population explosion.
Prolonging human life has also increased the dependency load. In all societies, people who are disabled or too young or too old to work are dependent on the rest of society to provide for them. In hunting and gathering cultures, old people who could not keep up might be left behind to die. In times of famine, infants might be allowed to die because they could not survive if their parents starved, whereas if the parents survived they could have another child. In most contemporary societies, people feel a moral obligation to keep people alive whether they
A. it was a moral responsibility to keep old-aged people alive
B. infants could be left dead in times of starvation
C. parents had to impart the cultural wisdom of the tribe to their children
D. death was considered to be freedom from hardships