The evidence presented in the excerpt supports the author's claim that fast food restaurants are like factories because the excerpt illustrates the assembly line principle of making things faster. (Last option)
Factories adopt the assembly line principle because it helps with the mass production that due to the products demand by the consumers or clients they (factories) have to produce. This principle also reduces the time it takes to produce a product, so that, there is more time available to produce much more. According to the author of the excerpt, something similar happens with the fast food restaurants, they have lots of clients and to properly serve to all of them, they don't spend much time making the food but instead, they buy it frozen and then cook it in the restaurant in order for them to save time and attend all clients and more.