The correct response is: The number of pro-slavery states exceeded the anti-slavery states after Texas joined the United States.
The annexation of Texas in 1845 was a significant turning point because it contributed to the growing sectional tensions over the issue of slavery in the United States. Texas was a slave state, and its admission into the Union increased the number of pro-slavery states, leading to a significant imbalance between pro-slavery and anti-slavery states. This contributed to the escalating conflict that would ultimately culminate in the Civil War.