which of the following could explain why the percentage of brown-shelled insects decreased from year 3 to year 4

I feel like you need a picture or graph for someone to answer this question. Being helpful, I'll guess some possible answers.

Nutrient or water shortages

Environment issues

Disease

Explanation:

because , habitat destruction, land use changes, deforestation, intensive agriculture, urbanization, pollution, climate change, introduction of invasive insect species, application of pesticides, mass trapping of insects using pheromones and light traps, pathological problems on

well, you see. the answer to your question is quite simple. the thing that is big, powerful, and over 9,000 is your mom.