4. At a table, there are four people: Luca, Maria, Nicola, and Paola. Each of the four always lies or never lies. Moreover, they do not like to talk about themselves, but rather about their friends; so when asked who among them always lies, their answers are:

Luca: "every girl is always honest"

Maria: "every boy is always a liar"

Nicola: "there is a girl who always lies, the other is always honest"

Paola: "one of the boys is always honest, the other never is".

Could you tell how many at the table are always honest?
(A) None
(B) 1
(C) 2
(D) 3
(E) all.
4. The answer is $\mathbf{( C )}$. Luca certainly cannot be telling the truth, since the two girls contradict each other, so they cannot both be telling the truth. If Maria were telling the truth, Nicola would be lying; therefore, it is not true that there is a truthful girl, and in particular, Maria is not, which is a contradiction. Therefore, Maria is lying. There must then be at least one boy who always tells the truth, and it must necessarily be Nicola. Therefore, according to what he says, one of the two girls is truthful, and since it cannot be Maria, it must be Paola. On the other hand, the latter states that there is only one boy who always tells the truth, and from what was deduced earlier, this statement is true. Therefore, the ones who are truthful are Nicola and Paola.