Error spotting in reported speech: As I was leaving for Delhi, he asked me whether I could buy a tape recorder for him. Decide whether there is any grammatical error in any part of this sentence.

Introduction / Context:
This question examines correct tense usage and clause structure in indirect speech. The sentence describes a situation where the speaker was about to travel to Delhi and another person made a request. The learner must check whether the time clause, the reporting clause, and the embedded request clause are all grammatically correct.

Given Data / Assumptions:
- Sentence: As I was leaving for Delhi, he asked me whether I could buy a tape recorder for him.
- The sentence begins with a time clause introduced by As.
- The main clause contains the reporting verb asked and a whether clause representing a polite request.
We assume a narrative context where the speaker is describing a past event.

Concept / Approach:
As I was leaving for Delhi is a correct time clause in the past continuous tense, showing an action in progress when something else happened. The verb asked can take an indirect question introduced by whether, and could is an appropriate modal in reported speech to show a polite request at the time of asking. The noun tape recorder is a standard object, and for him is the correct phrase to indicate the beneficiary. No part of the sentence violates grammar rules.

Step-by-Step Solution:
Step 1: Check the opening clause As I was leaving for Delhi. As is a suitable conjunction for showing time overlap, and was leaving is correct past continuous. Step 2: Examine the main clause he asked me whether. The verb asked followed by object me and the conjunction whether is a standard pattern for indirect questions. Step 3: Look at the content clause I could buy a tape recorder for him. The modal could is consistent with the past time reporting and expresses ability or willingness politely. Step 4: The object a tape recorder is grammatically correct, and the phrase for him correctly indicates on whose behalf the purchase would be made. Step 5: Combining all parts, the full sentence reads naturally and follows accepted rules for tense sequence and clause formation. Step 6: Therefore, there is no grammatical error in any part of the sentence.

Verification / Alternative check:
We can convert the sentence back into direct speech to verify it: As I was leaving for Delhi, he said to me, Can you buy a tape recorder for me. Turning this into indirect speech gives exactly the form in the question. This back and forth conversion confirms that the tense of could, the conjunction whether, and the rest of the structure are appropriate. Another variation might use if instead of whether, but whether is especially suitable when the choice is between yes and no, so the original is fully acceptable.

Why Other Options Are Wrong:
- Error in As I was leaving for Delhi: This is a well formed time clause, so no error exists here.

- Error in he asked me whether: This is the correct pattern for reported questions and polite requests, so it is grammatically sound.
- Error in I could buy a tape recorder for him: The clause is correct and uses a natural choice of modal for indirect speech.
- Error in more than one part of the sentence: Because no part needs correction, this option cannot be chosen.

Common Pitfalls:
Candidates may suspect errors simply because the sentence is slightly long and contains several clauses. They might also think that whether should be replaced by if or that could must be changed to would. However, in indirect speech many modal choices are possible, and could is often used to convey polite requests. It is important not to change correct sentences without a clear rule that has been violated.

Final Answer:
Correct option: No error in the sentence.