The lower mantle is composed of magnesium, iron-bearing silicates, olvine, and pyroxene.
The correct answer for the question that is being presented above is this one: "oxygen became available from cyanobacteria." About 1.2 billion years ago, eukaryotic and multicelled organisms evolved because oxygen became available from cyanobacteria.
I believe it is the high latitudes are very cold
Answer:
C
Explanation:
It was in a quizlet. Hope this helps!
