Which one of the following is not a female reproductive organ of flower?

In flowering plants (angiosperms), the reproductive organs are categorized into male and female parts:

• Female Reproductive Part (Pistil or Carpel): It consists of three main parts: the Stigma (receives pollen), the Style (a tube-like structure), and the Ovary (contains ovules).
• Male Reproductive Part (Stamen): It consists of the Anther and the Filament. The anther produces Pollen grains, which contain the male gametes.

Therefore, Style, Ovary, and Stigma are all components of the female reproductive system, whereas Pollen is the male gametophyte and is not a female reproductive organ. This makes option C the correct answer.