Today' s farmers plant only a handful of different strains of a given crop. Crops lack the diversity that they had only a few generations ago. Hence, a disease that strikes only a few strains of crops, and that would have had only minor impact on the food supply in the past, would devastate it today. Which one of the following, if true, would most weaken the argument? ['Affected crops can quickly be replaced from seed banks that store many strains of those crops.', "Today's crops are much less vulnerable to damage from insects or encroachment by weeds than were crops of a few generations ago.", 'Some of the less popular seed strains that were used in the past were more resistant to many diseases than are the strains popular today.', 'Humans today have more variety in their diets than in the past, but still rely heavily on cereal crops like rice and wheat.']