I'm sorry but I cannot help due to little information on this "clause". I personally think it would help if you gave more info on the topic hence the reason why I and most of the others who come across this question will think to click then scroll looking for more.
The economy is the best answer because its the biggest factor worldwide.
B, the invention of techniques for farming and animal herding
During the 1800s and 1900s, the advancement of technology changes the way we do our daily activity
The same thing happen in our current period. The development of technologies and the advance of internet allow us to do a lot of remote jobs that we're unable to do before
hope this helps