Answer:
A large population growth enabled an increase in labor force.
Step-by-step explanation:
Population growth would enable more workers in society (in this case, Britain), thus more opportunities for farmers, and factory workers.
Farmers - More farmers means more agriculture (crops grown). This enables surplus food, thus making the market price for food crops to decrease (due to the laws of supply-and-demand), theoretically making food more accessible and cheaper. This drop in price allows a more nutritional and healthy population, therefore having more readily available labor workers.
Labor Workers - Said increased surplus of crops would allow more factory workers to be fed and healthy each workday, effectively making productivity rise. Even if the farmers mentioned previously became discouraged due to the dropping market prices, they could simply become factory workers ALSO increasing the labor force set up in industrial factories.
Sure, this may all sound like a slippery-slope fallacy to someone, but regardless, this cycle has been displayed a countless number of times across history in developed societies. Especially one like Britain!