In this sentence improvement question on prepositions and historical wording, you must correct the expression "during the rein of Bahadur Shah Zafar" in the sentence "The revolt of 1857 happened during the rein of Bahadur Shah Zafar."

Introduction / Context:
This question tests both spelling and correct prepositional usage in a historical sentence. The phrase "The revolt of 1857 happened during the rein of Bahadur Shah Zafar" attempts to mention the period when Bahadur Shah Zafar was ruling. Examinations often check whether candidates can distinguish confusing homophones such as "rein" and "reign" and can choose the proper preposition that fits formal historical writing.

Given Data / Assumptions:

• Incorrect sentence: The revolt of 1857 happened during the rein of Bahadur Shah Zafar.
• The context is Indian history, specifically the First War of Independence in 1857.
• The underlined part is the phrase "during the rein of".
• We must select an alternative that is both spelled correctly and used with the right preposition.

Concept / Approach:
"Rein" refers to the strap used to control a horse and has nothing to do with ruling a country. "Reign" means "the period of rule of a monarch or ruler", which is the correct word when we talk about a king or emperor. For time periods, English often uses the expression "during the reign of" to link a historical event with the ruler under whom it occurred. Therefore, the correct idiomatic phrase is "during the reign of Bahadur Shah Zafar".

Step-by-Step Solution:
Identify that the sentence refers to a period when Bahadur Shah Zafar was the ruler.Recall that the noun for the period of rule is "reign", not "rein".Choose the preposition that matches time periods: "during the reign of" is standard.Form the corrected expression: "during the reign of Bahadur Shah Zafar".Insert it into the full sentence: "The revolt of 1857 happened during the reign of Bahadur Shah Zafar."

Verification / Alternative check:
Reading the improved sentence confirms that it sounds like normal textbook English: "The revolt of 1857 happened during the reign of Bahadur Shah Zafar." History books frequently use structures like "during the reign of Akbar" or "during the reign of Queen Victoria", so this phrasing is clearly correct and familiar.

Why Other Options Are Wrong:
Option A: "in the rein off" contains both spelling and preposition errors; "rein" is wrong and "off" is entirely incorrect here. Option B: "in the reign of" is grammatically possible but not as natural as "during the reign of" when specifying a particular historical event, and the exam expects the standard idiom. Option D: "No improvement" is wrong because "rein" is the wrong word and must be corrected to "reign".

Common Pitfalls:
Homophones like "rein", "rain", and "reign" commonly confuse learners because they sound very similar. It is important to connect each spelling with its distinct meaning: "rain" for water from the sky, "rein" for a strap controlling a horse, and "reign" for the rule of a king or emperor. Additionally, when describing historical events, "during the reign of" is a widely used fixed phrase that students should remember.

Final Answer:
The correct improvement is during the reign of, giving the full sentence "The revolt of 1857 happened during the reign of Bahadur Shah Zafar."