Explanation:

The correct answer is option 'b' - extinct species.

Definition of an extinct species:
An extinct species refers to a species that no longer exists and has no living members. Extinction occurs when a species cannot adapt to changes in its environment, faces competition from other species, or experiences catastrophic events that lead to its complete disappearance.

Dodo:
The dodo was a flightless bird that once inhabited the island of Mauritius in the Indian Ocean. It is widely recognized as one of the most famous examples of an extinct species.

Reasons for extinction:
There were several factors that contributed to the extinction of the dodo species:
1. Human arrival: When humans first arrived on the island of Mauritius in the 16th century, they brought with them invasive species such as rats, pigs, and monkeys. These animals preyed on dodo eggs and competed with the dodo for food sources, leading to a decline in the dodo population.
2. Habitat destruction: The clearing of forests for agriculture and the introduction of non-native plants also impacted the dodo's habitat and food sources.
3. Overhunting: The dodo had no natural predators on the island, and its lack of fear towards humans made it an easy target for hunting. The dodo's meat was highly sought after, and its population rapidly declined due to overhunting.

Confirmation of extinction:
The dodo was last sighted in the late 17th century, and since then, no confirmed sightings or physical evidence of living dodos have been found. The extinction of the dodo is widely accepted, and it is considered an extinct species.

Conclusion:
In conclusion, the dodo is an extinct species. It serves as a stark reminder of the impact that human activities can have on the environment and the importance of conservation efforts to protect endangered species and prevent further extinctions.

Dodo bird is an extinct species as it is not available anywhere on the earth