What a cruel suggestion. I cannot access that lesson. What we know thus far is that an adjective can essentially be used as a predicate without the need for any copula verb. When that happens, the order of the sentence is simply subject followed by adjective. That is what we have here, although when a noun is followed by an adjective, it may also simply be modifying the adjective and not making a statement as a predicate. So, please, either tell me yes, it can be a sentence with the addition of a period, or no, it would require some other structure. Or simply ignore the question.