In the following sentence, one part may contain an error. Identify the part with the error; if the sentence is correct, select "No error": No sooner did the sun rise (1) / when we resumed the journey (2) / after having a hasty breakfast. (3) / No Error (4).

Introduction / Context:
This sentence tests knowledge of another correlative structure used to show that one event happened immediately after another. The pair no sooner... than is very common in formal written English. In this question, however, the second part of the pair has been incorrectly replaced by when. Recognising this mismatch is the key to identifying the error.

Given Data / Assumptions:

• Sentence given: No sooner did the sun rise (1) / when we resumed the journey (2) / after having a hasty breakfast. (3) / No Error (4).
• Part 1: No sooner did the sun rise.
• Part 2: when we resumed the journey.
• Part 3: after having a hasty breakfast.
• The intended meaning is that the journey was resumed immediately after sunrise and after a quick breakfast.

Concept / Approach:
The fixed structure in English is no sooner... than, which emphasises that one event follows another with almost no delay. For example, No sooner did I reach home than it started raining. Using when after no sooner is incorrect and breaks this standard pattern. In the given sentence, when should therefore be replaced by than. Once this is done, the sentence reads correctly as No sooner did the sun rise than we resumed the journey after having a hasty breakfast.

Step-by-Step Solution:
Step 1: Identify the correlative expression beginning with No sooner did the sun rise in part 1.
Step 2: Recall that this must be followed by than, not when, to complete the standard pattern.
Step 3: Examine part 2, which begins with when we resumed the journey.
Step 4: Recognise that when is incorrect in this structure and should be replaced by than.
Step 5: Conclude that part 2 contains the error and that the corrected sentence should read No sooner did the sun rise than we resumed the journey.

Verification / Alternative check:
With the correction applied, the full sentence becomes No sooner did the sun rise than we resumed the journey after having a hasty breakfast. This version is grammatically acceptable and clearly indicates that the resumption of the journey closely followed sunrise. Keeping when, however, produces No sooner did the sun rise when we resumed the journey, which sounds wrong to a native speaker and violates the established no sooner... than pattern. This confirms that the wrong word lies in part 2.

Why Other Options Are Wrong:
Part 1 correctly uses the inverted form did the sun rise after no sooner. Part 3, after having a hasty breakfast, is grammatically fine and adds information about what had happened just before resuming the journey. Part 4, No Error, is only a label and is not part of the sentence itself. Since we have identified that when in part 2 should be than, the only part containing an error is part 2, making option B the correct answer.

Common Pitfalls:
Students often mix up the patterns of hardly and no sooner, leading to incorrect combinations like no sooner... when or hardly... than. The best way to avoid this is to memorise them as fixed pairs: hardly or scarcely... when, and no sooner... than. When doing error spotting, specifically check these words, because exam setters frequently test them. Practising several examples aloud can also help fix the correct combinations in memory.

Final Answer:
The error is in part 2; the word when should be replaced by than to form the correct expression no sooner... than.