In the following English grammar question on voice, choose the correct active form of the sentence: A hundred carefully-screened people were invited to dinner by the Prime Minister.

Introduction / Context:
This item checks whether you can convert a passive sentence into a clear, concise active-voice sentence. The given sentence is A hundred carefully-screened people were invited to dinner by the Prime Minister. In active voice, the focus shifts back to the doer of the action, the Prime Minister, while all important details about the number of people, the screening, and the dinner must be preserved without distortion or unnecessary additions.

Given Data / Assumptions:

• Passive sentence: A hundred carefully-screened people were invited to dinner by the Prime Minister.
• Agent (doer): the Prime Minister
• Verb phrase: were invited (past simple passive)
• Object (in passive subject position): a hundred carefully-screened people
• Complement: to dinner
• Task: Select the active sentence that keeps the same meaning, tense, and key details.

Concept / Approach:
To change passive to active, make the agent (by the Prime Minister) the subject of the new sentence and turn the passive verb into a simple past active verb invited. The group a hundred carefully-screened people becomes the object again, and to dinner remains as a complement indicating purpose. The most natural and efficient active sentence is therefore The Prime Minister invited a hundred carefully-screened people to dinner. It preserves the information that the screening has already been done and that those people were the invitees.

Step-by-Step Solution:

Verification / Alternative check:
To verify, convert the chosen active sentence back into passive: A hundred carefully-screened people were invited to dinner by the Prime Minister. This exactly matches the original sentence, confirming that no information has been lost or added and that the tense remains simple past. The modifier carefully-screened correctly refers to people and not to dinner. This makes option C the best and most accurate active-voice equivalent.

Why Other Options Are Wrong:
Option A (The Prime Minister invited a hundred people after screening them to dinner.) is awkwardly structured; after screening them to dinner is not idiomatic, and the careful screening is not clearly linked as a pre-modifier to people. Option B (The Prime Minister invited a hundred carefully screened people to have dinner with him.) adds with him, extra information not present in the original, and slightly shifts the focus. Option D (The Prime Minister invited to dinner a hundred persons who were carefully screened.) is grammatically acceptable but unnecessarily wordy; the clause who were carefully screened can be compressed into the simple adjective phrase carefully-screened as in the original. Option E simply restates the passive form with an extra detail at his residence, so it remains passive and introduces new information.

Common Pitfalls:
When changing voice, many learners either add new details (like with him or at his residence) or lose important modifiers such as carefully-screened. Another pitfall is producing grammatically heavy relative clauses where a simple adjective phrase would do. To avoid confusion, always ensure that your active sentence can be turned back into the original passive without changes in meaning or tense. Also look for the simplest, most natural word order: subject (doer) + verb + object + complement.

Final Answer:
The correct active-voice transformation is The Prime Minister invited a hundred carefully-screened people to dinner.