Correct Answer & Explanation
Option C
• The phrase 'By next year' indicates a deadline or a point in the future by which an action will be finished.
• This scenario requires the Future Perfect Tense, which describes an action that will be completed before a specific time in the future.
• The structure for Future Perfect Tense is Subject + will have + V3 (past participle).
• Therefore, 'will have completed' is the correct form.