Two family farms, run by Sandens and Brooks

Two family farms, run by Sandens and Brooks, use veterinary services provided by Walcor Insurance. One of Walcor`s services is the early detection in young cattle of a certain parasite that does not pose a threat to the animals` health but makes their meat unsuitable for consumption once they are full grown. If the parasite is first detected later, the insurance company has to cover the expense of rejecting the infected animal. Walcor offers a discount for the early detection procedure to Sandens, since they breed animals for meat and grow them to adulthood. However, since Brooks keep most of their cattle for only one season, from the point of view of financial logic, it makes no sense for Walcor to provide a similar discount to Brooks.

Which of the following, if true, most seriously weakens the argument?

A) Detecting a parasite in a young animal does not necessarily mean that its meat will be of bad quality later.

B) Some animals have natural resistance to the parasite.

C) Sandens buy large numbers of half-grown cattle from Brooks.

D) The two farms are of approximately the same size.

E) Animals owned by the two farms graze in different pastures.