※說明：第21至25題，請依照下列文章，選出最適當的答案。
        In the medical profession, technology is advancing so fast that questions of law and ethics cannot bediscussed and answered fast enough. Most of these questions involve ending or beginning a human life.For example, we have the medical ability to keep a person technically “alive” for years, on machines,after he or she is “brain dead,” i.e., after the “new brain” has stopped functioning. But is it ethical to dothis? And what about the alternative? In other words, is it ethical not to keep a person alive if we have thetechnology to do so? And there are many ethical questions involving the conception of a human baby. Invitro fertilization, for example, is becoming more and more common. By this method of conceiving ababy outside a woman’s body, couples who have difficulty conceiving a child may still become parents.This possibility brings joy to many families, but it also raises important questions. A fertilized human eggmight be frozen for a long time—perhaps decades—before it is implanted in the mother’s body. Is thisfertilized egg a human being? If the parents get a divorce, to whom do these frozen eggs belong? Andthere is the question of surrogate mothers. There have been several cases of a woman who is paid to carry(for the nine months of development) the baby of another woman who is medically unable to do so. Afterdelivering the baby, the surrogate mother sometimes changes her mind and wants to keep the baby.Whose baby is it? Is it the surrogate’s because she gave birth? Or is it the biological parents’?
【題組】21. What is the one main topic of the paragraph?
(A) Surrogate motherhood
(B) Methods of giving birth
(C) Keeping a person alive who is “brain dead”
(D) Ethical and legal concerns brought about by new technology in medicine