The main theme in the adventures of huckleberry finn that concerns the duke and dauphin is
a- friendship and loyalty
b-pretending to be what is not
c-slavery as a socially accepted intstitution
d- the duality between what is right and what is legal

B-pretending to be what is not

Explanation:

In Mark Twain's "The Adventures of Huckleberry Finn," the duke and the dauphin represent the fraudulence and dishonesty of society. In that respect, even though Huck realizes that they are not actually royals and that they are deceiving the villagers with their performance, the frauds' greed still put Huck and Jim in difficult situations.

in our power to make a world happy - to teach mankind the art of being so - to a character hitherto unknown - and to have, as it were, a new creation intrusted to our hands, are honors that command reflection, and can neither be too highly estimated,