Which of the following researchers are correctly matched with their work?
a. erwin chargaff demonstrated the assimilation of external dna into a cell; mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form
b. alfred hershey and martha chase showed that the dna, but not the protein, entered the bacterial cells, and was therefore concluded to be the genetic materiale. james watson and fredrick crick determined the structure of dna, an elegant double-helical model
c. frederick griffith x-ray diffraction of crystallized dna, suggested helical structure and diameter
d. rosalind franklin analysis of the relative base composition of dna