Bernard Davis Tested the "Cross-Feeding" Interpretation of Some Data That

Bernard Davis tested the "cross-feeding" interpretation of some data that showed the phenotype of one microbe as capable of being changed by another microbe.His contribution can be summarized as:

A) using one strain of microbes as food for another,and then evaluating the impact upon microbial phenotype.
B) combining microbes with complementing auxotrophs in a single tube and then analyzing the cells of gene exchange.
C) placing a barrier between bacterial strains with complementing auxotrophs to assess whether contact between cells was required for genetic exchange.
D) using fungi to feed bacterial strains with unusual auxotrophic mutations.
E) Davis was not a significant contributor to this research question.