The answer is b) They were dependent upon rivers for power
During the Industrial Revolution, Cotton was still imported from all over the British Empire to be processed for textiles.
Also, these factories wanted to hire all the help they could, so hire, men and women of all ages used to work in these factories.
Also, the factories only needed a handful of engineers to maintain the machines while rest of the work was repetitive and could be maintained by low-skilled workers.
However, almost all early cotton mills were located never water sources and rivers to power them with waterwheels.