I would say A because it is the starting numbers, and it is in order. Also because B and D are skipping a base ten number
The correct answer is A. In 771 BCE, Xi'an (the Zhou ruler) was attacked by an allied group of northern nobles and killed in battle, and in the following months, most of the western portions of the kingdom were lost to leaders of the vassal alliance to nomadic invaders who took advantage of internal divisions among the Chinese.
Social mobility is the movement of individuals, families, households, or other categories of people within or between social strata in a society. It is a change in social status relative to one's current social location within a given society.
The correct answer of this question is option C. It is because congress already meets nearly year-round. Special sessions are normally held for emergency situations. It is also called an extraordinary session because this happens during the time when the legislative body convenes outside of the normal session.