The correct structure of dna components can be presented as

Endangered

Explanation:

Endangered species are organisms that are at risk of extinction if deliberate efforts are not made to conserve them due to a rapid decrease in their population.

Hence, if a marine biologist writes an article about saving whales and labels them as endangered species, all efforts should be geared towards saving the animals lest they go extinct and leave a vacuum in the functioning of the ecosystem.  Every species have the critical roles they play in the functioning of the ecosystem and the extinction of any particular species represents a loss that might not be replaceable.