Characteristic of the Vessel elements of Angiosperms
It results in four genetically different cells
Working down mate, my best answer would be carbon monoxide, but I'm not studying exactly what you are. All those answers are logical except ozone.
There was no life on Earth for the first billion years because the atmosphere was not suitable for life. Earth's first atmosphere had lots of water vapor but had almost no oxygen. Later, frequent volcanic eruptions put several different gases into the air.
