OG详解-OG8 文法 Q14

Choice A is the best answer. The sentence emphasizes the aim of the research study by highlighting what the researchers conducting the study wanted to know—specifically, which factors influence clutch size among lizards. 
Choice B is incorrect because the sentence emphasizes what researchers determined at the end of the study, not what the study’s aim was. Choice C is incorrect because the sentence emphasizes a finding from the research study, not the aim of the study. Choice D is incorrect because the sentence emphasizes the research study’s methodology, not its aim.