Answer: "Without innovations in food production, the factories could not have grown so quickly."
This sentence is placed in the text as an example of how urbanization increased thanks to technological improvements. However, no other part of the text discusses food production. Also, the author does not explain how it is that food production contributed to the development of factories. Because it is only loosely related to the topic and it adds so few details, it is a superfluous sentence. It is possible to remove it without significantly affecting the rest of the text.
