Select the most appropriate option to fill in the blanks.

Christmas trees spread around the world, but the tradition began to have a ________ impact on forests, especially in Germany. As a result, Germans began making artificial goose-feather trees in the 1880s. These trees ________ different countries, and over time the goose feathers were replaced by other materials. A notable development occurred in the 1930s, when a manufacturer of toilet bowl brushes allegedly used surplus product to ________ an artificial tree.

The correct answer is Option D. The passage explains that Christmas trees had a detrimental impact on forests due to monoculture planting, making them vulnerable to pests and harsh weather. Additionally, the development of artificial trees using surplus materials is mentioned.

Option A: "Benign” means harmless or favorable, which doesn’t fit the context. The second blank should be filled with a verb, not a preposition. So this option is not suitable.

Option B : “Prolific” means abundant or productive, but it doesn’t convey the intended meaning of negative impact on forests. The second blank should also be filled with a verb. So this option is incorrect.

Option C: “Differential” doesn’t fit the context, and the verb tense is incorrect. This option is not the right choice.