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Choice D is the best answer. The convention being tested is subject-modifier placement. This choice ensures that the modifying phrase “despite being cheap, versatile, and easy to produce” appears immediately before the noun it modifies, “commercial plastics,” clearly establishing that the commercial plastics—and not another noun in the sentence—are being described as cheap, versatile, and easy to produce. 

Choice A is incorrect because it results in a dangling modifier. The placement of the function word “there” immediately after the modifying phrase illogically and confusingly suggests that “there” is cheap, versatile, and easy to produce. Choice B is incorrect because it results in a dangling modifier. The placement of the noun “two problems” immediately after the modifying phrase illogically suggests that the “problems” are cheap, versatile, and easy to produce. Choice C is incorrect because it results in a dangling modifier. The placement of the noun phrase “commercial plastics’ two associated problems” immediately after the modifying phrase illogically suggests that the “problems” are cheap, versatile, and easy to produce.