A sign stood at the gate of Aristotle College, which said "People who do not understand logic must not enter. " On this day, a group of people came, and they were all logic-savvy people. If the words on the brand are accurately understood and strictly enforced, then only one of the following assertions is true. which is the true assertion? ['They may not be allowed in.', 'They must not be allowed in.', 'They will definitely be allowed in.', 'They cannot be allowed to enter.']