OG4 阅读 Q25

Choice B is the best answer. In line 36 (Paragragh 3), the author explains that the initial transgenic studies were "lab-bound thought experiments come true." Those first studies, in other words, were considered to be of theoretical value only. They were not expected to yield products ready for human use.
Choices A and D are incorrect because the cost of animal research and the molecular properties of certain animals are not discussed in the passage. Choice C is incorrect because the passage does not suggest that all of the transgenic studies were focused on anticoagulants.