Convention of 1818 and the Haitian Revolution (or Rebellion) resulted in more territory for the United States (C).
The Convention directly resulted in more territory for the United States as Britain ceded all its territory South of the 49th parallel. On the other hand, the Haitian Revolution's contribution to US territory was rather indirect: having lost control over french Caribbean landholding influenced Napoleon Bonaparte’s decision to sell Louisiana. This lead to the Louisiana Purchase (1803) which almost doubled US territory.
