(单选题)Why does the author say “there was clear consensus that the practice of animal vivisection was not unethical (Para. 3)

A、 Because anesthetics were best understood in animal vivisections.
B、 Because anesthetics were mostly used in animal vivisections.
C、 Because the medical benefits of using animals in research were clear during this period.
D、 Because the medical benefits of using animals in research were waiting to be found out during this period.