More than one additional embryos can be formed in polyembryony from:
All of the above
When two or more embryos develop from a single fertilized egg, then this phenomenon is known as polyembryony. In humans, it results in forming two identical twins (monozygotic twins). This phenomenon is seen in both plants and animals.
In plants, this phenomenon is caused either due to the fertilization of one or more than one embryonic sac or due to the origination of embryos outside of the embryonic sac which can be from the cells of nucellus, integuments, synergids, etc. Sometimes the surrounding nucellar or integument cells start dividing and extend into the embryo sac. They develop into embryos.