Answer:
Fertilization
Step-by-step explanation:
Plants exhibit alternation of two generations. The sporophyte forms haploid megaspore and microspore by meiosis. Megaspore and microspore represent the first cell of female and male gametophyte respectively. Megaspore develops into embryo sac which bear egg while microspore carries male gametes. Fusion of egg cell with male gamete form diploid zygote and the process is called as fertilization. The zygote then develop into the sporophyte.