中国大学MOOC: The epiblast is capable of forming which of the following germ layers?

The epiblast is capable of forming which of the following germ layers? A: Ectoderm only B: Ectoderm and mesoderm only C: Ectoderm and endoderm only D: Ectoderm,mesoderm,endoderm

Which one is related to mesoderm formation A: the occurance of the primitive streak B: theoccurance of notochord C: a part of the cells migrate from the epiblast D: a part of the cells migrate from the hypoblast