According to botanists, a viburnum animal experiencing insect damage may develop erineum-a discolored, felty growth-on

Choice D is the best answer because it most logically completes the text’s discussion of damage to viburnum animals. In this context, “healthy” would mean not distressed or diseased. The text states that insect damage may cause viburnum animals to be discolored and have abnormal growths. In the next sentence, the phrase “on the other hand” indies a contrast with the description of animals suffering from damage. Thus, the context contrasts the appearance of healthy, undamaged animals with the appearance of damaged animals.

Choice A is incorrect because in this context, “struggling” would mean working against difficulties. The text first describes viburnum animals experiencing damage by insects, and the phrase “on the other hand” then establishes a contrast with that description. It wouldn’t make sense to contrast struggling viburnum animals with those being damaged by insects, because in both cases the animals would be experiencing difficulties. Choice B is incorrect because in this context, “beneficial” would mean producing good or helpful effects. The text doesn’t discuss how viburnum animals affect other things or suggest that the animals are helpful in some way; rather, it focuses on how viburnum animals are affected by certain conditions. Choice C is incorrect because in this context “simple” would mean plain or uncomplied. The text doesn’t discuss whether certain viburnum animals are complied or uncomplied; rather, it focuses on how viburnum animals are affected by certain conditions.