Choice D is the best answer. Every organically grown species represented in figure 2 produces a smaller yield than do their conventional counterparts. All of the organically grown species are within a range of approximately 60–90% of the conventional yield.
Choice A is incorrect because figure 2 shows that soybeans have the highest yield (approximately 90%), not the lowest. Choice B is incorrect because figure 2 shows that organically grown barley and maize are produced at a lower yield than the conventionally grown species (just below 70% and just below 90%, respectively), not a comparable one. Choice C is incorrect because figure 2 shows that soybeans, not tomatoes, have the highest yield of the organically grown species.