One factor that caused Texas to declare independence from Mexico was a. Mexican attitudes of racial superiority. b. a desire for unrestricted trade with the U. S. c. anger over the continued existence of slavery in Mexico. d. the decreasing numbers of immigrant settlers.

the decreasing numbers of immigrant settlers.

Explanation:

A convention of American Texans gathered at Washington and declared the independence of Texas from the country Mexico. The delegates who gathered at that event selected David Burnet as their provincial president and Sam Houston as the commander in chief of all Texan forces.  

The land in the area was so cheap and many American decided to settle there. The Mexican laws prohibited slavery but the Americans brought salves to Texas.  

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explanation:

under god i have placed my chiest strentgh and the safe guard to my loyal subjects