Which of the following is most likely responsible for the fact that organic molecules no longer formed spontaneously on Earth? A. The amount of UV radiation increased
B. The amount of oxygen in the atmosphere increased
C. Water accumulated in the oceans
D. Earth's surface temperature warmed

Which scientific design has both practical limitations and limitations due to scale? studying the effect of bleach on the growth of mold spores exposing cultures of duckweed to different intensities of light observing the replication of dna molecules with a hand lens using colored marbles to model a cross between two colors of rabbits