Consider the premise. Does the hypothesis naturally and logically follow? Premise: All five hijackers passed through the Main Terminal's west security screening checkpoint; United Airlines, which was the responsible air carrier, had contracted out the work to Argenbright Security. Hypothesis: None of the hijackers were able to pass the security screening checkpoint.
All five hijackers passed through the Main Terminal's west security screening checkpoint; United Airlines, which was the responsible air carrier, had contracted out the work to Argenbright Security.###None of the hijackers were able to pass the security screening checkpoint.