Almost all microbe species live together in dense, interdependent communities, supporting the environment for each other, and regulating the population balances for their different species through a complex system of chemical signals. For this reason, it is currently impossible to cultivate any one such species in isolation. Thus, microbiologists lack complete knowledge of most microbe species. Which one of the following, if assumed, enables the argument's conclusion to be properly drawn? ['If it is currently impossible to reproduce the environmental supports and chemical signals in dense, interdependent communities of microbe species, then it is also impossible to cultivate any microbe species from such a community in isolation.', 'At least some microbiologists lack complete knowledge of any microbe species that live together in dense, interdependent communities.', 'No microbe species that normally lives together with other microbe species in dense, interdependent communities can survive outside such a community.', 'No microbiologist can have complete knowledge of any species of organism unless that microbiologist can cultivate that species in isolation.']