11. The answer is $\mathbf{( C )}$.

Ludovico claims to be a scoundrel. This statement cannot be made by a scoundrel, because it would be true, nor by a knight, because it would be a lie. Therefore, Ludovico is a page, his second statement is false, and thus the first is true, meaning Orlando is a page. Then the first statement of Orlando is true, and therefore the second is false, that is, the three are not all pages. On the other hand, since Ludovico and Orlando are pages, this simply means that Drago is not a page. In conclusion, there are two pages: Ludovico and Orlando.

[Problem proposed by D. Lombardo.]
11) The hidden face of the moon is populated only by scoundrels, who always lie, knights who always tell the truth, and pages, who when they pronounce two consecutive sentences, lie in one and tell the truth in the other, choosing the order between the two randomly. Three inhabitants, Drago, Ludovico, and Orlando, make the following statements. Drago: "I am a page. Ludovico is a knight". Ludovico: "Orlando is a page. I am a scoundrel". Orlando: "I am a page. We are all pages!". How many of them are actually pages?

(A) 0 , (B) 1 , (C) 2 , (D) 3 , (E) it cannot be determined with the available data.