The correct answer is - B. raising livestock.
The people of Central Asia have been traditionally nomadic people, and that was their lifestyle until relatively recently. They were raising livestock, and their food source was heavily dependent on it, thus the constant moving over large ares, so that they were able to find nice grazing spots.
Even though nowadays, most of the people from this region are living in the cities and their life has significantly changed, there's still smaller portions of the populations that are practicing this traditional nomadic life with their livestock.
