The detail from the excerpt that best supports the claim that food was more consistently available in larger towns is that large towns are less vulnerable, being part of an international market that sees preserved foods traded long-distance; but much of the countryside is dependent on fresh food because, as seen, bigger towns had the advantage over the countryside of making trades with other global markets that bring into these towns conserved food, which at the same time impaired food trades with rural towns as an aftereffect since they were dependant of rather fresh food.