The experiment outlined below is a/an ________ test. The role of the rat liver homogenate is to ________.

A) pathogenicity; provide growth factors such as amino acids that the pathogen may require
B) pathogenicity; chemically modify the test chemical
C) Ames; control for spontaneous mutations
D) Ames; provide growth factors such as amino acids that the pathogen may require
E) Ames; chemically modify the test chemical