anchor: APHIS rejected the first alternative because it believed scientific evidence permitted importation of pork products from Sonora and not permitting such importation would be contrary to trade agreements entered into by the United States.
positive: Because they thought that scientific evidence permitted the import of pork products from Sonora, and not permitting that importation would be contrary to trade agreements by the United States, APHIS rejected the first alternative.
negative: APHIS accepted the first alternative because it did not permit the importation of pork products from Sonora.