In the following question, a sentence is given in direct speech. Select the option that best expresses the same sentence in indirect (reported) speech. My neighbour said, "I bought a new car last week."

Introduction / Context:
This last item involves reporting a simple statement about a recent purchase. The original uses simple past with the time phrase "last week". In indirect speech with a past reporting verb, the tense should be backshifted to past perfect and the time phrase must be changed. This pattern is extremely common in exam questions on reported speech.

Given Data / Assumptions:

• Reporting verb: "said" in simple past.
• Direct speech: "I bought a new car last week."
• Pronoun "I" refers to "he" in reported speech.
• Verb "bought" is simple past.
• Time phrase "last week" is relative to the original speaking time.

Concept / Approach:
When the reporting verb is in the past, simple past usually backshifts to past perfect in indirect speech. The time phrase "last week" is replaced by "the week before" or "the previous week" to match the new perspective of the person reporting the sentence later. The structure remains a simple statement introduced by the conjunction "that". No changes are needed in the object phrase "a new car".

Step-by-Step Solution:
Step 1: Introduce the reported clause with "My neighbour said that". Step 2: Change "I bought" to "he had bought". "Bought" is backshifted from simple past to past perfect, and the pronoun is changed from "I" to "he". Step 3: Keep "a new car" as it stands, as the object of the verb does not change. Step 4: Replace "last week" with "the week before" to represent the time correctly in indirect speech. Step 5: The complete reported sentence becomes "My neighbour said that he had bought a new car the week before."

Verification / Alternative check:
The reported sentence now clearly states that the purchase happened one week before the original statement and that this information is being reported later. The use of past perfect indicates that the buying happened before the time of reporting. The change from "last week" to "the week before" avoids confusion about exactly which week is referred to. The sentence is grammatically correct and faithful to the original meaning.

Why Other Options Are Wrong:
Option A keeps "last week", which is not natural in reported speech when the time has shifted. Option C uses "has bought", which is present perfect, and combines it with "the week before", which is not a standard combination. Option D uses "has bought" with "last week", but present perfect is not used with definite past time adverbials like "last week", so it is doubly incorrect.

Common Pitfalls:
Learners often hesitate about whether to change simple past to past perfect in reported speech, especially with time phrases. Another common mistake is to leave time expressions exactly as they appear in direct speech, which can create confusion for the reader. Exam preparation should include many practice items specifically on time phrase changes like "yesterday", "last week", and "tomorrow". That practice makes it easier to answer such questions quickly and confidently.

Final Answer:
The correct reported sentence is My neighbour said that he had bought a new car the week before.