The best answer is A. The last paragraph characterizes oligosaccharins as “specific chemical messengers”. The passage indicates that these chemical messengers are “specific” in that, unlike the pleiotropic hormones, they are likely to have particular effects on particular plant cells. Choice A is correct because it is the only answer choice that describes an effect on a specific aspect of plant growth and development: stimulating a particular plant cell to become part of a plant’s root system. Choice B and C are incorrect because the last paragraph indicates that enzymes activate the release of oligosaccharins. Choice D is incorrect because, although oligosaccharins do affect the activity of the gene complement of a particular cell, they do not duplicate that complement.