Final answer:
President Andrew Jackson's main problem with the Treaty of Velasco was that it did not adequately protect American interests and address the issue of Texas independence sufficiently.
Step-by-step explanation:
President Andrew Jackson's main problem with the Treaty of Velasco was that he believed it did not adequately protect American interests. Jackson felt that the treaty did not address the issue of Texas independence sufficiently, which was a concern for the United States at the time.
Therefore, option C) He thought it did not address the issue of Texas independence sufficiently, is the correct answer.