Oxygenic photosynthesis is made possible by the accumulation of oxygen in earth's atmosphere and oceans. the primary producers of oxygen from 2.4 billion to 650 million years ago were mostly

Cyanobacteria

Explanation:

Most Scientist believe that for half Earth's 4.6 billion years age there was no oxygen on the planet . The Cyano bacteria  or the blue green algae become the first microorganism to produce oxygen in the planet about 2.4 billion years from now. This was thought to happen somewhere between 2.5 and 2.3 billion years ago.

this is an example of "committed" time.

committed time, as contracted time, takes need over essential and available time since it is seen as profitable work. it alludes to the time allotted to keep up a home and family. at the point when a man is commuting using committed time this individual may feel that the drive is an obligation to family, for example, strolling youngsters to class or driving a mate to work. contracted and committed time clients may feel that their commute could really compare to the commute of important or leisure time clients on the grounds that their commute is profitable work. in this manner, they might be more disposed to pick a mechanized method of movement.