5. The atmosphere of early Earth is unlike today's atmosphere. A. When did oxygen first appear in Earth's early atmosphere? (3 points)

B. What factor caused the appearance of oxygen? (3 points)

C. What is one form of evidence used to support this theory? (4 points)

it's 5

Explanation:

today's atmosphere we enjoy today is radically different from the atmosphere that formed with the earth billions of years ago.

answer; the tunica intima also called tunica interna, consists of elastic fibers,connective tissue and smooth muscle cells;