Explanation
Correct answer: B.
Choice B is the best answer because it most logically completes the text’s discussion of beads found in Middle Stone Age sites. In this context, “ubiquity” means widespread presence or commonness. The text states that archaeologists have encountered “a plethora,” or an abundance, of beads made from Tritia gibbosula shells “in many Middle Stone Age (MSA) sites across western North Africa.” In this context, the abundance of beads therefore suggests their ubiquity.
Why the other choices are wrong
Choice A
Choice A is incorrect because in this context, “heterogeneity” would mean variety or diversity among the beads. The text doesn’t suggest that the beads varied significantly from one another; rather, it focuses on their widespread presence across multiple sites. Moreover, the text mentions that all the beads were “fashioned from Tritia gibbosula shells,” suggesting consistency rather than heterogeneity.
Choice C
Choice C is incorrect because the text doesn’t emphasize the beads’ “expediency,” or convenience or practicality. The text doesn’t support the idea of convenience (there’s no indication, for example, that the beads were easy to use or make) but rather focuses on the beads’ abundant presence at MSA sites.
Choice D
Choice D is incorrect. While “fecundity” can suggest abundant production, it specifically refers to fertility, and the text doesn’t connect the beads to this theme. Instead, the text attributes their widespread presence to the development of symbolic behavior in humans and the natural availability of Tritia gibbosula during the MSA.