How Do Genetic Mosaics Help Determine the Focus of Action

Multiple Choice

How do genetic mosaics help determine the focus of action of a gene?

A) Mosaics are composed of cells with different genotypes, so the phenotype of the cells that lack a gene product can be compared to that of neighboring cells that have the gene product.
B) Mosaics are created by mating flies that are homozygous recessive for two different genes and the morphology of the double mutant progeny is studied.
C) Mosaics are created by mating two flies that carry homozygous gain-of-function mutations in different genes and the effects of the mutations on the morphology studied.
D) Mosaics are created by the Cre-loxP system which allows for the deletion of specific genes at controlled stages of development.