Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes); nonhalophiles will not grow. Among the halophiles, mannitol fermenters will produce acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a non-halophilic mannitol fermenter and a halophilic mannitol fermenter. In this case, the medium is acting as (a) medium(s). a. differential
b. selective and differential
c. selective
d. enriched