Answer:
C. Forts
Step-by-step explanation:
While military forts in Texas may have helped indirectly to expand agriculture in the state, for example, by providing security services to farmers, especially in remote, and dangerous areas, a military fort does not directly help expand agriculture.
Texas could have had thousands of forts, and a very safe countryside, and still lack a strong farming sector.
Barbed wired fences, cotton gins, and windmills on the other hand, directly helped the expansion of agriculture. Barbed wired fences divided the farms, cotton gins promoted the cultivation of cotton, and windmill made easier to pruduce grains.