Biologist Rosanna Alegado believes that we might clearn how multicellalar organisms developed from single-celled ones if we understand why the single- celled organism Salpingoeca rosetta, the oldest living relative of animals,sometimes forms colonies cof cells. Alegado and colleagues reviewed,data from many studies about how S rosetta responds when exposed to another type of single-celled organism, bacteria , including Edward GRuby's work with Vibrio fischeri bacteria and Ana M. Cerdeño- ,c'Tárraga's work with Bacteroides fragilis bacteria. Alegado and colleagues concluded that neither V. fischeri nor B fragilis are likely to have played a significant role in the development of multicellular organisms. Which finding ,if true, would most directly support Alegado and colleagues conclusion? A S. rosetta tended to form colonies when exposed to V. fischeri and when exposed to B. fragilis. B S. rosetta tended to form colonies when exposed to V. fischeri, but not when exposed to B. fragilis. C S. rosetta tended to form colonies when exposed toeB. fragilis, but not when exposed to V. fischeri. D S. rosetta did not tend to form colonies when exposed to either Vo fischeri or B fragilis.