Read each sentence to find out whether there is any error in any part As you know(a) that the ignorant(b) are easily duped(c). No error.(d)

'Are’ needs to be replaced with ‘is’ to make the sentence contextually correct. This is because, ‘in subject verb agreement, we match the subject with the nearest verb or the verb with the nearest or the first subject. But the verb should be matched with the main subject of the sentence’. Here the main subject is ‘Ignorant’ which is singular and so is followed by a singular verb.