Why do we believe the Cambrian explosion occurred so suddenly?
A) oxygen concentrations reached critical levels necessary to support more complex life
B) organisms became sufficiently complex that more diversity became possible
C) climate change due the end of the last snowball Earth phase
D) all of these
D
You might also like to view...
A ray of light traveling through water passes through an air bubble. Which path does it take?
A. A B. B C. C D. D E. E
The magnetic force on a circular loop of wire of radius r carrying current I around it is zero N
Indicate whether the statement is true or false
Free Fall: When a ball is thrown straight up with no air resistance, the acceleration at its highest point
A. is upward. B. is downward. C. is zero. D. reverses from upward to downward. E. reverses from downward to upward.
A person weighing 200 pounds stands on snowshoes. If the area of each snowshoe is 400 square inches, the pressure on the snow is
a. 0.25 psi. b. 0.5 psi. c. 2 psi. d. 4 psi. e. none of the above.