Mapping Studies Have Determined That Within a Group of Mutants

Mapping studies have determined that within a group of mutants with the same growth requirements (i.e. ,the same overt phenotype) ,individual mutations are on different chromosomes.This indicates that

A) the same gene governs all the steps in a particular biological pathway.
B) different genes can govern different individual steps in the same biological pathway.
C) different genes govern the same step in a particular biological pathway.
D) all biological pathways are governed by different genes.
E) genes do not govern steps in biological pathways,but proteins do.