|Question 14Verbal

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Biologist Rosanna Alegado believes that we might learn how multicellular 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 of cells. Alegado and colleagues reviewed data from many studies of how S. rosetta responds when exposed to another type of single-celled organism, bacteria, including Tristan Barbeyron's work with Zobellia galactonovorans bacteria and Yoshihide Matsuo's work with Zobellia uliginosa bacteria. Alegado and colleagues concluded that both Z. galactonovorans and Z. uliginosa might have played a role in the development of multicellular organisms.
Which finding, if true, would most directly support Alegado and colleagues' conclusion?
S. rosetta tended to form colonies when exposed to Z. galactonovorans and when exposed to Z. uliginosa.
A
Although several studies involving other bacteria species found that S. rosetta tended to form colonies after bacteria exposure, only the studies using Z. galactonovorans and Z. uliginosa tested whether the amount of bacteria exposure affected the rate of colony formation.
B
S. rosetta tended to form colonies when exposed to Z. uliginosa but not when exposed to Z. galactonovorans.
C
S. rosetta tended to form colonies when exposed to Z. galactonovorans but not when exposed to Z. uliginosa.
D