Answer:
The correct answer is option B, assuring a habitat remains unharmed
Step-by-step explanation:
Among all the given options , human activities preserving the ecosystem is depicted in option B where human is not trying to disturb the ecosystem. While in all other options, hunting a species upto extinction will create disappearance of an species from ecosystem, introducing toxic compound to a food web will lead to transfer of toxic compound to each trophic level and in the last option D, even if a new species is introduced in the food web, it will destablize the food web thereby making the ecosystem as unstable.