The life cycle of a plant is characterized by an alternation of generations between a haploid gametophyte and a diploid sporophyte.

Here's the breakdown:

* Gametophyte (n): This is the haploid generation. It produces gametes (sperm and egg) through mitosis.

* Sporophyte (2n): This is the diploid generation. It produces spores through meiosis.

Therefore, the answer is 2n.

In summary:

* Gametophyte (n) → Mitosis → Gametes (n) → Fertilization → Zygote (2n) → Mitosis → Sporophyte (2n) → Meiosis → Spores (n) → Mitosis → Gametophyte (n)