Option (D) is correct. The context states that 'Stamen is the male reproductive part and it produces pollen grains that are yellowish in colour.' The anther is the part of the stamen that contains pollen grains. The other options are incorrect because: sepals are non-reproductive parts of the flower mentioned separately; ovules are contained in the ovary (the swollen bottom part of the pistil); and pistil is the female reproductive part, distinct from the stamen. The anther, being part of the male reproductive structure (stamen), contains pollen grains which carry the male germ-cells.