(a) He is one of those few postcolonial writers who believes (b) that this talk about colonialism has gone too far (c) and has turned into a cliche. (d) NO ERROR
(A) a
(B) b
(C) c
(D) d

Hint: The question suggests that we need to find the part of the sentence which has any error in it. If not, we will select the option d which states No Error. To find the error in the above sentence, we will analyse each sentence carefully for any grammatical errors.

Complete answer:
Let us discuss all the options in detail to find the correct one.
A) He is one of those few postcolonial writers who believes: This part of the question has an error. The error lies in the word ‘writer’ as in this part we are talking about ‘one of those few’, that means we are referring to a group here. Here, the word ‘writer’ which is in singular form, should be in plural form, ‘writers’. This part can be correctly written as ‘He is one of those few postcolonial writers who believes’. Therefore, this is the correct option.
B) That this talk about colonialism has gone too far: This part of the sentence is correct as it doesn’t contain any error. Therefore, this is an incorrect option.
C) And has turned into a cliché: This part of the sentence is correctly formed as it doesn’t contain any error. Therefore, this is an incorrect option.
D) No error: This option is incorrect as the error lies in option a.

Hence, the correct answer is option ‘A’.

Note: The part with an error (if any) is the correct answer, otherwise option d will be the answer. But since, we have encountered the error in part a of the sentence, option a remains our answer.