Questions: As a congressman from Tennessee, strongly supported annexing Texas and occupying the Oregon territory. Sam Austin Henry Clay Martin Van Buren James K. Polk

The answer is James K. Polk.

Sam Austin is not a well-known historical figure in the context of U.S. congressional history or territorial expansion. This option is not relevant to the question.

Henry Clay was a prominent American statesman and politician who served in both the House of Representatives and the Senate. He was known for his efforts in the American System and his role in the Missouri Compromise, but he did not strongly support the annexation of Texas or the occupation of the Oregon territory.

Martin Van Buren was the 8th President of the United States and a key figure in the Democratic Party. However, he did not strongly advocate for the annexation of Texas or the occupation of the Oregon territory during his political career.

James K. Polk, the 11th President of the United States, was a strong proponent of Manifest Destiny, the belief that the U.S. was destined to expand across the North American continent. As a congressman from Tennessee, he strongly supported the annexation of Texas and the occupation of the Oregon territory. His presidency is marked by significant territorial expansion, including the acquisition of Texas, Oregon, and the Mexican Cession following the Mexican-American War.