Ans. (a). structure B.
The pollen grains are defined as microscopic bodies, which contains male gametes and fuse with female gametes during fertilization. In angiosperms (flowering plants), pollen grains are developed in the anther (a part of stamen or male reproductive organs).
The process by which pollen are formed is known as microsporogenesis and involves meiotic division in a microspore mother cell to form four daughter microspores.
In given diagram, label A, B, C, and D represent ovule, anther, stigma, and petal, respectively. Thus, the correct answer is option (a).
