Question

About 1.2 billion years ago, eukaryotic and multicelled organisms evolved because _____.

oxygen became available from cyanobacteria

banded iron formations developed

meteorite impacts increased

the atmosphere got thicker from volcanic outgassing

Answer 1

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.