Answer: The correct answer for the blank is- Anther, stigma.
Fertilization ( process of fusion of male and female gamete) in flowering plants takes place when pollen ( containing male reproductive cell that is sperm) produced from anther ( male reproductive part) is transferred to the stigma ( a part of female reproductive system).
It then moves through a pollen tube ( style) that follows stigma and enters the ovule ( bearing eggs) of the ovary. Finally, fusion of male and female gamete takes place.