Suppose that Janzen had found no difference in survival rates of acacia trees in his control and experimental groups. Which conclusion would he have drawn?
a. The ants are parasites because they offer no benefit to the trees.
b. A mutualistic relationship must exist because trees are not harmed by the ants.
c. A mutualistic relationship may exist because trees may benefit in some way (e.g., reproductive success) not revealed by this experiment.
d. There is no mutualistic relationship because only one organism has been shown to benefit from the relationship.