Which of these is unique to flowering plants?
1) a dominant sporophyte generation
2) an embryo surrounded by nutritive tissue
3) haploid gametophytes
4) pollen production
5) double fertilization

Double fertilization. (Ans. 5)

Explanation:

Double fertilization is a complex fertilization process occurs only in flowering plants known as angiosperm. In this process two male gametes or sperm cells fertilization occurs, first one is fertilized with the egg and form the zygote and second one is fuses with the 2 polar nuclei which cause the formation of endosperm.

In double fertilization, after the process of fertilization, the tissue of ovary forming the fruit and fertilized ovule of an ovary forming the seed.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).