Improve the bracketed part of the sentence to form a correct and idiomatic English structure: (As soon as I saw) the ferocious dog than I ran away.

Introduction / Context:
This question tests knowledge of a very common correlative conjunction pattern in English: no sooner and than. The original sentence uses the construction As soon as I saw the ferocious dog than I ran away, which is not standard. The exam asks you to choose the improved version of the bracketed part so that the complete sentence sounds correct and idiomatic. Such questions are frequent in competitive exams because they test your familiarity with formal structures that show immediate sequence of events.

Given Data / Assumptions:

• The original sentence is: As soon as I saw the ferocious dog than I ran away.
• The bracketed part is As soon as I saw.
• Options include variants using No sooner and different verb forms.
• The intended meaning is that the speaker ran away immediately after seeing the dog.

Concept / Approach:
In English, when we use no sooner to express a very quick sequence, it is normally followed by an auxiliary verb and subject in an inverted order, and the second clause starts with than. The standard structure is: No sooner did subject verb than subject verb. For example, No sooner did I reach the station than the train left. In this structure, did is used with the base form of the main verb. So, we must choose an option that uses No sooner, an auxiliary, and the base form see in correct order. We also need to ensure it matches the second clause than I ran away.

Step-by-Step Solution:
Step 1: Observe that the original sentence incorrectly mixes As soon as with than. If we keep As soon as, we should use than as soon as when is not required, so this combination is faulty. Step 2: Recognise that exam questions often want you to convert As soon as clauses into No sooner clauses with inversion. Step 3: Examine option a, No sooner than I saw. This puts no sooner directly before than, which is incorrect structure. The correct pattern is No sooner did I see than I ran away. Step 4: Examine option b, No sooner has I seen. This uses has with I seen, which is ungrammatical, and also does not match the past simple context suggested by ran away. Step 5: Examine option c, No sooner did I see. This follows the pattern no sooner plus auxiliary did plus subject I plus base verb see and fits well with the following than I ran away. Step 6: Examine option d, no improvement. This would keep the faulty combination As soon as I saw with than, which is not standard English. Step 7: Therefore, the correct improvement is No sooner did I see, making the full sentence No sooner did I see the ferocious dog than I ran away.

Verification / Alternative Check:
To verify, compare two parallel sentences: As soon as I saw the ferocious dog, I ran away and No sooner did I see the ferocious dog than I ran away. Both convey the same meaning of immediate reaction. Notice that the no sooner sentence uses did I see and than I ran away, which is a well known formal pattern. The other options fail to match this pattern either because they misplace than or use a wrong auxiliary. Grammars for competitive exams frequently provide examples exactly like No sooner did he arrive than it started raining, reinforcing that option c follows the correct template.

Why Other Options Are Wrong:
Option a, No sooner than I saw, is incorrect because no sooner must be followed by an auxiliary verb and subject, not directly by than.
Option b, No sooner has I seen, is wrong because has I seen is not correct subject auxiliary order and does not match the simple past context.
Option d, no improvement, is incorrect since the original As soon as I saw the ferocious dog than I ran away mixes two patterns improperly and is ungrammatical.

Common Pitfalls:
A common pitfall is to focus only on the words no sooner and than and ignore the need for inversion of auxiliary and subject. Learners often write No sooner I saw than, which is also wrong. Another mistake is to use the past perfect without proper context, such as No sooner had I seen the dog than, which can be correct in some cases but is not among the given options here. Always remember the core pattern no sooner did subject verb than subject verb for simple past narration of immediate events.

Final Answer:
The correct improved expression is No sooner did I see, so option c is correct.