14. When did cyanobacteria start producing pure oxygen? O A. After the Hadean eon
O B. During the Hadean eon
O C. After the Proterozoic eon
O D. During the Phanerozoic eon

Lomexico, central america, and the caribbean: mastery testselect the correct answer.which of the following was the leading cause of death among native americans after the arrival of europeans? a.conquistadorsb.diseasec.starvationd. warreset

Identify the type of weathering seen in each picture ? chemical weathering mechanical weathering

How far is a geographic second? a.) around 100 feet b.) around 1,000 feet c.) around 5,000 feet d.) none of the above