In the following error spotting sentence, read the labelled parts and decide which one (A), (B), (C) or (D) contains an error: I was surprised (A) / when the hostess smiled (B) / as if she saw me before. (C) / No error (D).

Introduction / Context:
This question tests your understanding of tense usage in conditional or comparative clauses introduced by as if. The sentence describes a past situation in which the hostess smiled in a way that suggested she already knew the speaker. To express this idea correctly, English normally requires a past perfect tense in the as if clause. You must examine the labelled parts and identify which part contains the tense error that disrupts the correct expression of prior action relative to another action in the past.

Given Data / Assumptions:

• Part (A): I was surprised
• Part (B): when the hostess smiled
• Part (C): as if she saw me before.
• Part (D): No error.
• The intended meaning is that the hostess behaved as though she had seen the speaker at some earlier time.

Concept / Approach:
When English speakers describe an unreal or hypothetical situation in the past, especially after expressions like as if or as though, they often use the past perfect tense to show a prior and somewhat unreal action. In this sentence, the main actions were I was surprised and the hostess smiled, both in the simple past. The clause as if she saw me before attempts to suggest an earlier experience that is only implied. The correct tense to convey that sense is had seen rather than saw. Therefore, the phrase should be as if she had seen me before. Parts (A) and (B) use standard simple past forms and are acceptable, but part (C) uses the wrong tense for this structure, making it the segment with the error.

Step-by-Step Solution:

Verification / Alternative check:
To verify, rewrite the full sentence in corrected form: I was surprised when the hostess smiled as if she had seen me before. This version clearly expresses that the hostess smile gave the impression of prior acquaintance. If we keep as if she saw me before, the sequence of tenses is less precise and does not fully capture the idea that the seeing, if it happened, would have been earlier than the moment of smiling. Additionally, grammar rule books often illustrate as if clauses with past perfect when implying a counterfactual or earlier condition. This supports our choice of part (C) as the incorrect segment.

Why Other Options Are Wrong:
Part (A), I was surprised, is perfectly correct as a past tense statement of reaction. Part (B), when the hostess smiled, properly uses simple past to describe a completed event that triggered the surprise. There is no grammatical issue in these parts. Part (D), No error, is incorrect as an answer because we have clearly identified that part (C) uses saw where had seen is more appropriate. Thus, the only correct choice for the location of the error is option C.

Common Pitfalls:
Students sometimes overlook subtle tense shifts inside subordinate clauses, especially when the main clause seems straightforward. Another common mistake is to treat saw as an acceptable general past tense in all contexts, without considering whether the clause expresses an earlier or hypothetical action. Exam setters often use as if to test knowledge of this specific tense pattern. To avoid such errors, pay special attention whenever you see as if or as though, and check whether the situation described is unreal or prior to another past event. In such cases, the past perfect is usually the safer and more accurate choice.

Final Answer:
The error is in part (C), so the correct answer is C.