Human Embryos Differ from Bird Embryos in That

Human embryos differ from bird embryos in that

A) human embryos do not undergo cleavage.
B) human embryos have a yolk sac, but it contains very little yolk.
C) human embryos have no yolk sac.
D) bird embryos have an extra membrane, the allantois, that is not found in human embryos.
E) bird embryos undergo metamorphosis to become sexually mature adults.