详解
Choice B is the best answer. The first paragraph of the passage identifies and describes "Texas gourd vines" (line 1,"Texas...flared"), but the primary focus of the passage is introduced in the first sentence of the second paragraph: "In one recent study, Nina Theis and Lynn Adler took on the specific problem of the Texas gourd—how to attract enough pollinators but not too many beetles" (lines 17-20,"In...beetles"). The remainder of the passage focuses on describing the purpose, process, and results of the recent research done on those Texas gourd vines.
Choice A is incorrect because the passage doesn't focus on the assumptions behind a theory but rather on the way in which that theory was tested. Choice C is incorrect because the passage does not present much conflicting data; most of it supports the idea there can be too much fragrance for the Texas gourd vine. Choice D is incorrect because the passage explains the procedures used in a study were "'very labor intensive'" (line 58,"It was...Theis") but does not present them as particularly innovative.