Answer:
In 1841, President Lamar sent the Texas Navy to support Mexican rebels in the Yucatan. The Yucatan was in the midst of a rebellion against the central government of Mexico, and Lamar saw an opportunity to support the rebels and potentially gain an ally in the region. The Texas Navy, which was composed of several ships, provided naval support to the rebels and helped to secure their victory in the Yucatan. Therefore, option B, the Yucatan, is the correct answer.