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

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

Style
Ovary
Pollen
Stigma
This question was previously asked in
UPSC CISF-AC-EXE – 2019
Pollen is the male gametophyte of a flower.
The female reproductive part of a flower is called the pistil or carpel, typically consisting of three parts: the stigma (receives pollen), the style (stalk connecting stigma to ovary), and the ovary (contains ovules, which develop into seeds). The male part is the stamen, consisting of the anther (produces pollen) and the filament.
Style, Ovary, and Stigma are all components of the pistil/carpel, which constitutes the female reproductive organ(s) of a flower. Pollen grains are produced by the anthers, which are part of the male reproductive organs (stamens).