The correct answer is B.
The industrial revolution brought spectacular technological improvements that led to huge productivity gains in the manufacturing sectors that started to demand a very high number of employees. On the other hand, there was an excess of labor in the agricultural sector that, at those times, employed the majority of the population and it had also become highly unproductive.
Therefore, there was a movement of labor from the unproductive agricultural sector to the productive manufacturing sector. This movement was attached to the transfer of people from the countryside, where agricultural activities were located, to urban areas, where factories were located.
I'm not sure but it can be a force that pulls objects with mass towards it.
