In the following question, a sentence has been given in Passive Voice. Out of the four alternatives suggested, select the one which best expresses the same idea in Active Voice: "The room was cleaned."

Introduction / Context:
This question tests basic conversion from passive voice to active voice when the doer of the action is not mentioned. The sentence given is "The room was cleaned." In passive sentences like this, the agent is either unknown or unimportant. You must select the active version that best preserves this meaning without adding extra information that is not present in the original sentence.

Given Data / Assumptions:

• Passive sentence: "The room was cleaned."
• Subject in passive: "The room."
• Verb tense: simple past passive (was cleaned).
• No agent phrase such as "by me" or "by the cleaner" is given.
• Options include various active sentences with different subjects.

Concept / Approach:
When the passive sentence does not mention who performed the action, the most neutral active conversion uses an indefinite subject like "someone" or "they". This avoids adding specific information that is not in the original sentence. If we switch to "I" or "the cleaner", we introduce a new agent that the original sentence did not specify. Therefore, a generic subject is preferred for an accurate transformation.

Step-by-Step Solution:
Step 1: Identify the action and tense: "was cleaned" indicates simple past cleaning.Step 2: Recognise that the passive sentence does not tell us who cleaned the room.Step 3: To convert to active, we need a subject. A neutral way is to use "someone" if the doer is unknown.Step 4: Construct the active sentence: "Someone cleaned the room."Step 5: Compare this with the options and select the one that matches.

Verification / Alternative check:
Check meaning: "The room was cleaned" simply indicates that the cleaning took place. "Someone cleaned the room" also indicates that the cleaning took place, without specifying who did it. Both sentences are equivalent in terms of known information. If we choose "I cleaned the room", we now claim that the speaker is the cleaner, which the original sentence never stated. Hence, "Someone cleaned the room" is the closest active equivalent.

Why Other Options Are Wrong:

• The cleaner cleaned the room: Introduces a specific agent "the cleaner", which is extra information not present in the passive sentence.
• The room should be cleaned: Changes both tense and meaning, suggesting a recommendation instead of completed action.
• I cleaned the room: Again adds a specific agent, the speaker, which the passive sentence did not mention.
• They clean the room: Uses simple present tense and suggests routine action, not a single completed cleaning in the past.

Common Pitfalls:
Many learners try to "guess" a logical agent such as "the cleaner" or "the maid" when converting passive to active. However, exam questions check faithfulness to the original sentence. Unless the agent is clearly specified, you should not add a new specific subject. Use "someone" or "they" to preserve the uncertainty.

Final Answer:
The best active voice version of "The room was cleaned" is "Someone cleaned the room."