Answer: I think it's A
Explanation: Did some research, Hopefully that's right because it said that the emperor was taken over by the military
<span>Population size is closely linked to its rate of change. If the population is below the threshold for the resources available, it will increase in size ... The more distance between the actual size and the threshold, the greater the rate of increase. If the population is above its threshold, it will start to decrease in size. The threshold will be the equilibrium position so it will tend to wave up and down until it gets to the equilibrium. The reason real life populations don't do this is because the resources are changing all the time so the equilibrium is a moving target.</span>
The first three options I see are all making-decision process to take action, but the last one is the one that is not like that. Researching is something that is not so close in meaning to what you need. That is why, D is a good option.
Caucasus Mountains is your answer
