The correct answer is D. They may kick up dust and pollute Earth's atmosphere.
Step-by-step explanation:
The impact of a large asteroid or comet is a major event that leads to major changes in ecosystems. One of the effects that can be expected is an important increase in dust because one of the components of asteroids and comets is dust, which would be released during the impact. Also, this dust might interact with components from the soil and the atmosphere creating a cloud, acting as a pollutant. According to this, the expected effect is "They may kick up dust and pollute Earth's atmosphere"