In the following sentence, identify the part that contains a grammatical error and choose the correct option: 'She was an only child who had been very welcome.'

Introduction / Context:
Error-spotting questions test your understanding of English grammar and natural usage by breaking a sentence into parts and asking you to locate the incorrect portion. Here, the sentence 'She was an only child who had been very welcome.' looks almost correct at first glance, but there is a tense and usage issue that sounds unnatural in standard English. You must identify which part contains the error and understand why it is considered wrong in this exam context.

Given Data / Assumptions:

Sentence: 'She was an only child who had been very welcome.'
Parts: (A) 'She was an', (B) 'only child who', (C) 'had been very welcome.', (D) 'No error in the sentence.'
We assume the speaker is describing her general situation in the family, not a temporary event.
We must select the part that contains an inappropriate verb phrase or tense.

Concept / Approach:
The phrase 'an only child' is a fixed and correct expression meaning the person has no siblings. The verb 'was' correctly introduces a past description of her status. The problem lies in 'had been very welcome', which uses the past perfect tense 'had been'. The past perfect is typically used to refer to an action completed before another past action. In this sentence, there is no second past reference point that justifies the past perfect. Moreover, the usual expression is 'she was very welcome' or 'she had been very much welcomed' in a specific context. Therefore, the form in part (C) sounds grammatically and stylistically wrong for standard exam English.

Step-by-Step Solution:
Step 1: Check part (A) 'She was an': the phrase 'She was an only child' is a correct and common way to describe someone with no siblings. Step 2: Check part (B) 'only child who': this smoothly connects to a relative clause 'who was very welcome' or similar; no error lies here. Step 3: Check part (C) 'had been very welcome.': the use of 'had been' suggests a time earlier than another past action, but the sentence provides no such later past reference point. Step 4: Recognize that the intended meaning is likely a simple past state: she was very welcome in the family, or her birth was very welcome, rather than a complex earlier event. Step 5: Conclude that part (C) is the erroneous portion; it should be rephrased as 'was very welcome' or similar.

Verification / Alternative check:
We can test alternative versions: 'She was an only child who was very welcome' sounds natural and grammatically correct. Another version, 'She had been very welcome before her brother was born', would justify the past perfect, because there is a clear later past event. However, the given sentence does not mention any later event; it describes a single past state. Therefore, simple past 'was very welcome' is the correct tense choice, and 'had been very welcome' is an overuse of the past perfect, which examiners treat as an error.

Why Other Options Are Wrong:
Part (A) uses 'an only child', which is a standard expression, not 'the only child' in this context. Part (B) contains the relative clause connector 'who', which is correctly placed after 'only child'. Part (D) claims that there is 'No error in the sentence', which is false because the tense in part (C) is inappropriate. Thus, only part (C) contains a grammatical and usage error that needs correction.

Common Pitfalls:
Many learners are taught that the past perfect 'had' makes English sound advanced, so they use it even when simple past is sufficient. This leads to sentences like 'She had been very happy' without a second past event to anchor the timeline. Competitive exams often test this misuse. Another pitfall is overthinking the phrase 'an only child' and wrongly believing the article 'an' is incorrect. In fact, 'an only child' is perfectly standard; the error is in the tense choice in part (C).

Final Answer:
The incorrect part is Part (C) – 'had been very welcome.'