Step 1: Male gametophyte development.
The pollen grain (microspore) has two cells: the vegetative cell and the generative cell.
Step 2: Division of generative cell.
The generative cell undergoes mitotic division to form two male gametes (sperms), which take part in double fertilization.
Step 3: Conclusion.
Thus, the cell that divides to form two male gametes is the Generative cell.