Concept:Emphatic stress highlights the word that provides the specific information a question is asking for.
Explanation:When a word is in capital letters, it carries the strongest stress in the spoken sentence.
That stressed word is the answer to the missing information in the question you must choose.
The correct question replaces the stressed word with the appropriate question word, so the stressed word itself is not repeated in that option.
For example, when the sentence is "SHE works at the hospital," the emphasis is on "SHE," the person who works there.
The question that needs "SHE" as its answer is "Who works at the hospital?"
Options B, C, and D all keep the subject "she" because they ask about other details such as place, confirmation, or activity.
Option A, however, asks about the subject without repeating the stressed word.
Answer:A. Who works at the hospital?