Choice B is the best answer. In (lines 61-63"incline...few"), the author explains that Dial named his scientific finding "WAIR, for wing-assisted incline running, and went on to document it in a wide range of species." In this context, Dial "documented," or recorded, the existence of WAIR in numerous bird species.
Choices A, C, and D are incorrect because in this context, "document" does not mean to portray, publish, or process.