Which of the following is shown as a heavy blue line with triangles?
A) dry line
B) warm front
C) cold front
D) occluded front
Question 2
The evolution to an oxygen-rich atmosphere:
A) was heavily dependent upon aerobic bacteria.
B) would have occurred even if carbon dioxide had not been present.
C) occurred at the same time the atmospheric levels of carbon dioxide were decreasing.
D) required large amounts of atmospheric nitrogen.
