In the sentence "I was living in Chennai for ten years when I was a child.", the underlined verb phrase must reflect a finished situation in the past. Choose the option that best improves this phrase, or select No improvement if the sentence is already correct.

Introduction / Context:
This sentence improvement question examines your understanding of the correct tense to describe a past state that extended over a definite period and is now completely finished. The sentence refers to the speaker's childhood, a completed phase of life, and specifies a duration of ten years. The task is to select the verb form that best expresses this completed state in simple past time.

Given Data / Assumptions:

• Sentence: I was living in Chennai for ten years when I was a child.
• The underlined part is was living in Chennai.
• Options: had lived, lived, had been living, No improvement.
• The time frame is clearly in the past and is connected with the speaker's childhood.

Concept / Approach:
When we talk about a general state or habit that continued for a period in the past and is now finished, English usually uses the simple past tense, not the past continuous or past perfect, unless there is a special reason to emphasise ongoing activity or sequence. The sentence refers to a place where the speaker lived for ten years during childhood, which is a typical use of simple past: I lived in Chennai for ten years when I was a child. The past continuous was living is not needed here and sounds unnatural with the duration phrase for ten years.

Step-by-Step Solution:
Step 1: Identify the nature of the action. Living in Chennai is a state, not a single event, and it lasted for ten years in the past. Step 2: Recognise that this state is completed and tied to a finished time period when I was a child. Step 3: Recall that for finished states and habits over extended periods in the past, the simple past is preferred: lived. Step 4: Replace was living with lived, giving I lived in Chennai for ten years when I was a child. Step 5: Evaluate option B, lived, which matches this corrected form. Step 6: Evaluate option A, had lived, which would make sense mainly in relation to another past reference point, which is not emphasised here. Step 7: Evaluate option C, had been living, which again introduces a past perfect continuous aspect that is unnecessary and overly complex for a simple background statement.

Verification / Alternative check:
Compare with similar sentences: I lived in Delhi for five years as a student, She lived in that village for a decade before moving to the city. In all such examples, simple past is used. We only move to past perfect or past perfect continuous when contrasting two past times, such as By the time I left Chennai, I had lived there for ten years. The original sentence has no such second time reference; it simply gives a background fact about childhood, so simple past is the correct choice.

Why Other Options Are Wrong:
Had lived and had been living both suggest a comparison with another specific later past event, and without that comparison, they sound unnecessary or overly formal. No improvement would keep was living, which tends to be used for temporary or interrupted actions and is less suitable with a clear and completed ten year period.

Common Pitfalls:
Many learners overuse continuous tenses because they think they sound more advanced. However, in many past time statements the simple past is not only sufficient but also preferred. A good rule of thumb is to use simple past for stable situations and habits in a finished period unless there is a clear need to emphasise ongoing action at a particular moment or to establish a time contrast that calls for past perfect forms.

Final Answer:
The correct improvement is lived, giving: I lived in Chennai for ten years when I was a child.