Answer:
Option D, Earth is below carrying capacity
Step-by-step explanation:
The population of any species with in an ecosystem can grow maximum up to the carrying capacity of that ecosystem and until unless this carrying capacity is met, the population of this species keeps on growing at a rapid level.
This is exactly the case with earth. The carrying capacity of planet earth has not been yet reached (or the resources required to sustain human population have not yet been consumed to the fullest level) and that is why the human population is growing exponentially.
Therefore, the correct answer is option D