Answer:
This blank space in this question is COMPETE
Step-by-step explanation:
This question is describing natural selection, which is the theory proposed by Charles Darwin where he stated that organisms that are better suited for an environment will survive and reproduce better than others.
In the environment, resources such as food, water, mate etc are limited, hence, organisms must COMPETE for the available ones. In this case, organisms that are better adapted will triumph over others. Therefore, it is certain that not all organism that are born can be supported by the environment because organisms COMPETE for resources.