Step 1: Pollen grains consist of two main cells: the vegetative cell, which controls the growth of the pollen tube, and the generative cell, which divides to form two male gametes.
Step 2:
- (A) One vegetative and one male gamete: Incorrect, as the male gametes are formed from the generative cell.
- (B) Two male gametes: Incorrect, because the generative cell divides into two male gametes after the pollen tube formation.
- (D) One generative cell and one male gamete: Incorrect, since the generative cell gives rise to two male gametes.
Conclusion: Pollen grains consist of one vegetative cell and one generative cell, making \( (C) \) the correct answer.