Need ! plzz
which statement explains why the organisms that require oxygen today owe their existence to the early autotrophs on earth?

(a)autotrophs cleaned earth’s water so that modern organisms could drink it.
(b)autotrophs produced oxygen as a waste product, which built up in the atmosphere.
(c)autotrophs used the methane that was present in early earth’s atmosphere.

B) Autotrophs produced oxygen as a waste product, which built up in the atmosphere.

Explanation:

Autotrophs feed off carbon dioxide as an energy source and release oxygen in exchange.

Hope this helps! :)

the only other powers were germany russia and uk and they were too busy fighting each other wearing each other down   that the us was becoming strong and they were becoming weaker

the answer is blue river