Answer is A. Nucleus.
Flower is the reproductive organ of a flowering plant that contains male reproductive organ ( stamen) and female reproductive organ (carpel). Anther of the stamen produces male gamete and within the ovary of the carpel produced female gamete. After fertilization male gamete and female gamete fuses to form zygote. Zygote is a single cell whose nucleus has chromosomes, where all the genetic information regarding development of fruit and seed are stored.