Final answer:
A species becomes extinct when the last member dies, often due to inability to adapt to environmental changes or competition for resources.
Step-by-step explanation:
When a species cannot respond to environmental changes, members of that species begin to die. When the last member of a species dies, the species becomes extinct. Extinctions are a part of natural selection and are often a result of a species not having the traits needed to survive in a changed environment, a concept known as Survival of the Fittest. Sometimes, a species faces interspecific competition, where it is outcompeted for resources by another species, leading to extinction. Environmental changes can be drastic and unpredictable, causing some species to not adapt in time, resulting in their extinction.