Answer:
Firstly, how did black death spread? Well, spread majorly by flea-ridden rats on boats and fleas which comfortably remained on the passages, which further led to this event. Moreover, when food was transported this lapsed good food since it carried bacteria(the black plague). This resulted in towns becoming infested with the black plague. Therefore, trolley traveling of food resulted in the major contamination as food is a necessity as it encouraged the spread of the bacteria.
