What is not true about the archean eon?
a. oldest fossil is found from this time period
b. formation of earliest solid rock
c. oxygen begins to appear in the atmosphere
d. spanned from about 3.8 billion to about 2.5 billion years ago

D. Spanned from about 3.8 billion to about 2.5 billion year ago

Explanation:

The Archean eon expanded from 4 billion years ago, until 2.5 billion years ago, being predeceased by the Hadean eon, and being followed by the Proterozoic eon. During this eon there were numerous very important things that happened. The first solid rocks were formed, thus the basis for the first continents arrived on the scene. The oldest fossils of living organisms are also dated to this eon, and they were the ones that started to slowly change the atmosphere by introducing free oxygen molecules to it.

it would be f

explanation:

a tetrad is the foursome during meiosis made by two homologous chromosomes that have each already replicated into a pair of sister chromatids.