The occurrence of more than one embryo in a seed is referred to as :

Polyembryony

The correct answer is Option (3) -polyembryony.

In many Citrus and Mango varieties some of the nucellar cells surrounding the embryo sac start dividing, protrude into the embryo sac and develop into the embryos. In such species each ovule contains many embryos. Occurrence of more than one embryo in a seed is referred to as polyembryony.

Apospory and Apogamy : Formation of embryo from any other cell of embryo sac (other than egg) without fertilization .

Fertilization : It can be defined as the fusion of the male gametes (pollen) with the female gametes (ovum) to form a diploid zygote

Parthenogenesis : Formation of embryo from unfertilized egg.