The sentence is divided into four segments: (A), (B), (C), and (D). Identify the segment that contains a grammatical error. If the sentence is both grammatically and contextually correct, select “No error” as the correct answer.

The ambassador (A)/ said the reports have (B)/ being examined carefully by his staff (C)/ before making any comment. (D)

The correct option containing the grammatical error is C.

Let us analyze the sentence step-by-step to identify the error:
1. Analyze the structure and tense: The sentence starts in the past tense with "The ambassador (A)/ said...". This reporting verb introduces indirect speech.
2. Identify the verb phrase in the subordinate clause: The subordinate clause uses "...the reports have (B)/ being examined carefully by his staff (C)...". Here, "have being" is grammatically incorrect.
3. Determine the correct form: The action describes something that happened before the reporting verb "said" (in the past). Furthermore, since the reports are receiving the action, the verb must be in the passive voice. The auxiliary "have" (which should be "had" to maintain past tense agreement with "said") must be followed by the past participle "been", not the present participle/gerund "being". Thus, the correct phrase is "had been examined" or "were being examined".
4. Locate the error: The word "being" in segment (C) is incorrect and should be replaced with "been" (to form "had been examined" or "have been examined") to make the sentence grammatically correct.

Therefore, segment (C) contains the grammatical error.