Mismatched premises and conclusion. (A) proceeds by presenting a set (the lowest bidders on a contract), but it does not restrict this set to only two members. It instead presents the conditional statement Contract Not To Lowest Bidder→Caldwell. It then validly concludes that the absence of the necessary condition leads to the absence of the sufficient condition. The stimulus, meanwhile, restricts a set to two members, and then concludes that one member must be chosen if the other isn’t.

(B) proceeds by presenting a set (the lowest bidders on a sanitation contract) and then giving a conditional statement that restricts this set to only two possible members (either Dillon or Ramsey). It then reaches the valid conditional conclusion that, if a member of this set is being chosen, and it’s not Dillon, then it must be Ramsey.

Mismatched conclusion. (C) proceeds by presenting a set (those awarded the landscaping contract) and then giving a conditional statement that restricts this set to only two possible members (either Kapshaw or Johnson). (C) validly concludes that Kapshaw must be chosen if Johnson is not chosen, but it brings up the irrelevant idea of the lowest bidder. The stimulus does not bring up any irrelevant ideas in its conclusion, so (C) doesn’t match.

Mismatched premises and conclusion. (D) proceeds by presenting a set (the lowest bidders on a contract), then giving a conditional relationship that shows that if Holihan is not a member of this set, then neither is Easton. It then invalidly concludes that, if a member of this set is being chosen and it’s not Easton, then it won’t be Holihan either. The stimulus, however, restricts membership of a set to two individuals before reaching a valid conclusion, so (D) doesn’t match.

Mismatched conclusion. (E) proceeds by presenting a set (the lowest bidders on a catering contract) and then giving a conditional statement that restricts this set to only two possible members (either Perez or Sullivan). It then reaches the valid conditional conclusion that, if neither Perez nor Sullivan is chosen, then a member of their set will not be awarded the contract. The stimulus, meanwhile, restricts a set to two members, and then concludes that one member must be chosen if the other isn’t.