Scientists Alan M.Goldberg and Thomas Hartung describe recent advances in replacing the use of animals in toxicology testing.Improvements in cell and tissue culture technologies,for example,allow a growing number of tests to be performed on human cells alone.Computer models are becoming increasingly complex and many could one day become more accurate than trials in living animals. Since the late 1990s,Huntingdon Life Sciences--a company that conducts testing of substances on animals conducted by the Environmental Protection Agency and the Food and Drug Administration--has become a proving ground for aggressive strategies by animal-rights militants  .At a hearing,a Senate.committee listened to testimony  against Huntingdon employees and financial institutions providing services to the company.One experimentation witness at the hearing insisted that any means necessary were justified  to spare animals' lives;he has previously accepted the idea of murder to that end. Use of animals in testing and in biomedical research continues to be necessary in many instances and is ethically preferable to experimenting on humans or giving up cures that could save human lives.But for the sake of people and animals alike,the development and acceptance of animal substitutes deserve enthusiastic support. In some instances, substitutes are already thought as good or better than animals,but supervising agencies have yet to catch up.In both the European Union and the U.S.,scientists and companies wanting to use the new alternative tests complain that regulatory standards for proving a drug or chemical to be safe for humans force the continued use of animals.Thus,animal-loving Americans might turn to persuading the EPA and the FDA to speed validation of new methods so that they can be more widely employed.And animal advocates  who want to influence business could consider investing in the small biotech's and large pharmaceutical  companies that are working to develop alternatives to animals in research. The writer's attitude towards replacing the use of animals in toxicology is  _  .
arbitrary(,) pessimistic indifferent( ) optimistic
Question: Scientists Alan M.Goldberg and Thomas Hartung describe recent advances in replacing the use of animals in toxicology testing.Improvements in cell and tissue culture technologies,for example,allow a growing number of tests to be performed on human cells alone.Computer models are becoming increasingly complex and many could one day become more accurate than trials in living animals. Since the late 1990s,Huntingdon Life Sciences--a company that conducts testing of substances on animals conducted by the Environmental Protection Agency and the Food and Drug Administration--has become a proving ground for aggressive strategies by animal-rights militants  .At a hearing,a Senate.committee listened to testimony  against Huntingdon employees and financial institutions providing services to the company.One experimentation witness at the hearing insisted that any means necessary were justified  to spare animals' lives;he has previously accepted the idea of murder to that end. Use of animals in testing and in biomedical research continues to be necessary in many instances and is ethically preferable to experimenting on humans or giving up cures that could save human lives.But for the sake of people and animals alike,the development and acceptance of animal substitutes deserve enthusiastic support. In some instances, substitutes are already thought as good or better than animals,but supervising agencies have yet to catch up.In both the European Union and the U.S.,scientists and companies wanting to use the new alternative tests complain that regulatory standards for proving a drug or chemical to be safe for humans force the continued use of animals.Thus,animal-loving Americans might turn to persuading the EPA and the FDA to speed validation of new methods so that they can be more widely employed.And animal advocates  who want to influence business could consider investing in the small biotech's and large pharmaceutical  companies that are working to develop alternatives to animals in research. The writer's attitude towards replacing the use of animals in toxicology is  _  .
A. arbitrary(,)
B. pessimistic
C. indifferent( )
D. optimistic
Answer: