The right answer is Administrators. They take part of the Office of Administration which its main role consists in providing the administrative support to the Executive Office of President. It includes financial management, research assistance, human resources, information technology, security, etc. The director of this office manages the yearly budget and related requirements of the organization of the official funding panel.
D. kept people from settling farther west.
China imposed One-Child Policy in China after the decline of infant mortality from 1978-1980. The Chines government wanted to regulate the population. This happened because of their growing population. Song Jian, one of the top Chinese officials had found out about the books of Limits of Growths and Blueprints of Survival, because of this, Song Jian had estimated a population of 700 million on that year.