The Spanish attempted to ward off future threats on present-day California byA. building a great wall.

b. building missions.

c. enslaving Native Americans to stand guard.

d. none of the above

the correct answer is (B) building missions.

The missions were built by the Spanish starting the year 1769 in order to "colonize" the territory of Alta California, which they had discovered over two centuries earlier. The mission system required that Indians brought into a mission by being baptized into the faith and through this they could become"civilized." This was considered a big plus for supporting the use missions as the central element in colonization.