Beadle and Tatum Irradiated Neurospora and Initially Grew the Mutant

Beadle and Tatum irradiated Neurospora and initially grew the mutant strains on complete medium. How were they able to determine the type of mutation for each strain?

A) By growing the mold on a complete medium with extra vitamins and nutrients
B) By growing the mold on minimal media supplemented with different combinations of amino acids and vitamins
C) By growing the mold in its diploid form to see which traits were masked
D) By comparing Neurospora to other species of mold
E) By observing the marked differences in morphology between the different strains