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.
It had a very positive impact because the 1920's was when many new technologies were introduced, one example being the the assembly line, which made many industries more productive and profitable.
Hope that helps!
