Correct Answer:
C. will have completed
This question requires choosing the correct verb form to indicate an action that will be completed by a specific point in the future. The key phrase here is "By next year," which signals the need for the future perfect tense.
The future perfect tense is used to describe an action that will be completed before a certain time or another action in the future. Its structure is will have + past participle. In this context, "she will have completed her PhD" means that the action of completing the PhD will be finished at or before the end of next year.
- A: "completes" is the simple present tense, used for habitual actions or scheduled future events, which doesn't fit the 'completion by a future point' context.
- B: "will complete" is the simple future tense, indicating an action that will happen in the future. While she will complete it, the phrase "By next year" specifically emphasizes completion *before* that future deadline, making the future perfect more precise.
- D: "completed" is the simple past tense, referring to an action that finished in the past, which is incorrect for a future event.
Therefore, C: "will have completed" is the correct choice, as it accurately conveys that the action of completing her PhD will be finished by the specified future time.