Chordates are animals that possess certain characteristics including a notochord. Humans fall into this category along with many vertebrates such as whales, falcons etc; therefore, all of the answers apply.
Food, research, therapy, entertainment affection.
Oxygen entered the Earth's atmosphere after the appearance of the Great Oxidation Event (Great Oxygenation Event). The Great Oxidation is the first mass extinction on Earth.
The Great Oxidation lasted 2.4 to 2.0 billion years ago.
Oxygen appeared on Earth thanks to cyanobacteria using photosynthesis.
<span>pelican would be the answer to this</span>