Based on historical facts, the only true statement from the above is 1. Many Southern leaders argued that they had voluntarily joined the Union as sovereign states and had the right to leave the Union if they chose.
It is indeed true that a lot of Southerners believed that they could leave the United States whenever they wanted to.
It is not true that Southerners thought their problems were over when Abraham Lincoln was elected as they wanted to secede even more.
Governor Houston was known to have tried to stop Texas from seceding.
In conclusion, option A is correct.
Find out more on Sam Houston at https://brainly.com/question/1399699.