Scientists want to estimate the time when two species began evolving separately from a common ancestor. What would be the most useful strategy for calculating this estimate?
A. Comparing DNA sequences from each species for the same gene
B. Comparing DNA sequences from each species for different genes
C. Comparing the length size or weight of an average member of each species
D. Identifying the traits of the common ancestor

Juan and carol were studying invertebrates in biology. they knew that segmented or earth worms preferred a dark, moist habitat. during this lab, they would be investigating the responses of organisms called planaria or dugesia tigrina. these were simple flatworms that still had a one-way digestive system and a very simple nervous system. juan and carol placed the planaria in a petri dish containing cool, distilled water that was partially covered with black paper. they shined a light on the dish. next, they removed the paper and placed a small amount of chicken liver at one end of the dish. they added a few large salt crystals to the water. finally, they added drops of hot water to the cool water in the petri dish. their results can be seen in the data table. according to their experiment, all but one conclusion is valid.