In Drosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end.
62) The next step after the embryo is formed would be
A) division of the embryo into five broad regions.
B) use of pair-rule genes to divide the embryo into stripes, each of which will become two segments.
C) use of zygotic segment polarity genes to divide each segment into anterior and posterior halves.
D) enclosure of the nuclei in membranes, forming a single layer over the surface.
E) separation of head, thoracic, and abdominal segments of the embryo.