Answer: d. The ecosystem reached its carrying capacity, and was not able to support continued population growth.
Explanation:
The carrying capacity can be defined as the maximum population size of the species that habitat or ecosystem can support or sustain on the basis of availability of food, water and other necessities. This is an important factor which keeps a balance of the population of a species in a particular region or ecosystem.
On the basis of the above information, The ecosystem reached its carrying capacity, and was not able to support continued population growth is the correct option to level off the rising populating of the birds.
