Answer:
D. the establishment of a new government
Step-by-step explanation:
The divisions between eras in Texas history are determined on the basis change in the political patter or government.
Texas history is divided in different eras such as the age of contact in which Columbus' voyage formed Texas in 1492; Spanish colonial, the era in which Spanish entered in North America and took the reign; Mexican national era in which Mexican got independence from Spain; Revolution and Republic era, in which Texas got Independence from Mexico; and Civil War in which conflicts between Mexico and Texas raised and the United States won the war.
Hence, the Texas history is majorly divided on the "D. establishment of a new government".