Select the segment of the sentence that contains the grammatical error. If…

English chooses the indefinite article by the SOUND that begins the next word, not by its spelling: use 'a' before a consonant sound and 'an' before a vowel sound. This applies to letters and abbreviations too, since they are judged by how they are pronounced — for example 'an MBA', 'an SMS', and 'an X-ray' — even when the written first letter is a consonant.

In this sentence, segment (A) reads 'Karun has a X-ray machine.' 'X-ray' is pronounced 'eks-ray,' so it begins with the vowel sound /e/, not a consonant sound. The article before it must therefore be 'an', not 'a' — making 'a X-ray machine' the grammatical error in the sentence.

• (B) 'which is very significant for' — a correctly formed relative clause; no article, tense, or agreement fault.

• (C) 'him due to many reasons.' — 'due to' is used here as a standard preposition meaning 'because of', which is accepted in current usage, so this segment is not a grammatical fault.

• (D) 'No error' — cannot be correct once a genuine fault (the article before 'X-ray') is present in one of the other segments.

Correct sentence: 'Karun has an X-ray machine, which is very significant for him due to many reasons.' The grammatical error is in segment (A).