Correct Answer:
C. was drinking
The correct answer is C: was drinking. This sentence uses the Past Continuous tense, which is employed to describe an ongoing action in the past that was interrupted by another, shorter past action. The action of "drinking tea" was in progress when the guest arrived, which is the interrupting event. The Past Continuous is formed with "was/were" + verb-ing.
- A: drinks is Present Simple, used for habitual actions.
- B: drank is Past Simple, indicating a completed action, not an ongoing one that was interrupted.
- D: has drunk is Present Perfect, used for actions completed recently or with a result relevant to the present.
The structure "She was drinking tea when the guest arrived" perfectly illustrates an ongoing past action interrupted by a sudden past event.