Concept:Pollination is the transfer of pollen from the male part (anther) to the female part (stigma) of a flower.Explanation:The key is to separate pollination from later steps. Germination of pollen grains and growth of pollen tube occur after pollination. Visiting flowers by insects is a means of pollination, not the definition itself. The precise definition is the transfer of pollen from anther to stigma. Fertilization happens later, after pollen tube reaches the ovule.Answer:Option D: transfer of pollen grain from anther to stigma.