In this active and passive voice question, the sentence "I had to stop all my work to complete this project." is given in active voice. Select the option that best expresses the same idea in passive voice.

Introduction / Context:
This question tests your ability to change a sentence from active voice to passive voice while preserving both meaning and tense. The original sentence "I had to stop all my work to complete this project." focuses on the subject "I" and describes a necessity in the past: it was necessary for me to stop my work. When converting to passive, the focus shifts from the person performing the action to the work that had to be stopped, while keeping the idea of necessity intact.

Given Data / Assumptions:

• Active sentence: "I had to stop all my work to complete this project."
• Subject: "I".
• Object: "all my work".
• Modal-like structure: "had to stop" (past necessity).
• Purpose clause: "to complete this project".
• The goal is to produce a passive sentence that expresses the same necessity about the work, not to merely rephrase in active voice.

Concept / Approach:
In passive constructions with "have to" or "had to", we use the pattern: object + had to be + past participle. Here, "all my work" is the object that will become the subject in passive voice. The verb "stop" turns into "be stopped". The phrase "to complete this project" remains as a purpose clause and does not need to change in voice. The agent "by me" can be omitted because it is obvious from context and not essential to the meaning.

Step-by-Step Solution:
Step 1: Identify object in active voice: "all my work". This will become the subject in passive voice. Step 2: Identify the necessity structure "had to stop". In passive voice, this becomes "had to be stopped". Step 3: Keep the purpose clause "to complete this project" unchanged at the end of the sentence. Step 4: Combine these elements to form "All my work had to be stopped to complete this project." Step 5: Check options. Option A exactly matches this correct passive construction. Step 6: Verify that the tense (past necessity) and meaning (work had to be stopped) have both been preserved.

Verification / Alternative check:
Examine the other options. Option C simply restates the original active sentence with a slight change of word order; it is not passive at all. Option B changes the modal from "had to" to "must", which changes the time reference and strength of necessity. Option D uses "had been stopped", which describes a completed past state, not an obligation in the past. Option E changes the structure and may suggest that the stopping of work and completing the project were two separate events, rather than expressing necessity. Therefore, only option A is a clean passive version of the original sentence.

Why Other Options Are Wrong:
Option B incorrectly uses "must" instead of "had to", altering the tense and tone. Option C does not change voice at all and keeps the sentence active. Option D uses past perfect passive ("had been stopped"), suggesting that all work was already stopped before some other past event, which is not what the original sentence says. Option E is grammatically possible but shifts the emphasis away from necessity and into a more descriptive narrative of two events. For exam purposes, it is not the best equivalent transformation.

Common Pitfalls:
Students often pick options that look grammatically correct without checking whether the voice has actually changed. Another common error is ignoring the modal "had to" and switching to "must" or "should", which changes the meaning. To avoid such mistakes, always follow a clear process: identify subject, verb, and object, then use the correct passive pattern, and finally compare the tense and meaning with the original sentence.

Final Answer:
The correct passive voice transformation is All my work had to be stopped to complete this project.