Answer:
The correct answer is option B) "they are having a positive impact on the environment by acting as decomposers".
Explanation:
Beetles in the forest have a positive impact on the environment by acting as decomposers when they eat limbs of trees that have fallen to the forest floor. The trees that lose limbs do not longer need the organic matter than the limbs have. This organic matter re-enters to the cycle of life by decomposers such as the beetles, that eat them and have a positive effect by "recycling" this matter.