The statement that best explains the role of slavery in Texas's decision to secede from the Union is:
"Slavery was an important part of the Texas economy, and the fear of abolition caused Texas to secede from the Union."
This statement accurately reflects how the economic reliance on slavery and the apprehension regarding its potential abolition played a crucial role in the secessionist sentiment in Texas. While other factors may have contributed to the decision, the preservation of slavery was a central concern for many Texans at the time.