I don't know if that is a trick question but I think that I see a problem with it!
Horatio is definitely a liar, because if he were telling the truth then all of the other 3 would have to be liars, which is not the case. That rules out B, C and E.
Answer D is clearly wrong because 2 people supposedly telling the truth contradict each other.
So, the obvious answer is A - Bernard and Inigo are the ones telling the truth. Their statements do not contradict each other. The other 2 statements are lies.
The problem is that we are not given the option of selecting F - Alfred and Inigo, which could also be true!