About Oxygen?

Question

I did some hard reasearch but I coudlt find out anything about the following questions

I answered for the question (WHAT IS OXYGEN USED FOR?)

and answered

Oxygen is a very common yet vital element and used in many things. First, it is an element used to make water which is needed for life, H2O. Secondly, it is the gas which we breathe in for respiration.

And I cant answer the question
-WHY THE GAS HAVE THESE USES?

And the Last question I need help on is
-HOW THE GAS COULD BE OBTAINED?
-

Edit:So um wats does that answer

Answer 1

Oxygen is given off by plant life, making breathing for us possible.

It also helps force out carbondioxide molecules and various other deseases/bacteria, funguses, spores.

There are books on Oxygen therapy, as well as Water therapy, which also has two parts oxygen to one part hydrogen.

Answer 2

this gas have this use because the human system is compatible with this gas.

there are many natural and synthetic methods to obtain this gas, the most common of all being is the natural process of photosynthesis by plants in the day.