cell type but a whole organ. A stunning example of such transcriptional control comes from studies of eye development in the fruit fly Drosophila. Here, a single transcription regulator called ____ triggers the differentiation of all of the specialized cell types that come together to form the eye. Flies with a mutation in this gene have no eyes at all, which is how the regulator was discovered. It is a master transcription regulator, which sits at the apex of the regulatory networks for the target genes.A．EyeB．EyC．YesD．Eys