After Another Doubling of Its Population by 1800, China Moved

After another doubling of its population by 1800, China moved toward what some historical demographers have called a high-level equilibrium trap, a condition in which:

A) A country's neighbors are trapped into accelerating the level of reproduction in order to keep up with a rival's burgeoning numbers.
B) Radical improvements in crops or technology is inevitable, given the large number of potential inventors.
C) A "one-child" policy leads to a demographic imbalance, in which baby girls outnumber baby boys by a factor of 2:1.
D) The land has reached its maximum potential for feeding a population, and the surplus population begins to starve.