Answer:
The correct option is B) Competition for resources increased, which increased the death rate.
Step-by-step explanation:
The maximum number of organisms of a species that a place can hold is termed as the carrying capacity of that place. When the number of organisms in a community increases beyond the carrying capacity, the resources t support these organisms become lesser as compared to the organism number. As a result, competition begins between the organisms to for these resources. Most of the organisms die due to lack of resources, others might migrate and hence the population begins to decline.