By the time she arrives, the meeting will have started.
- NO CHANGE (correct answer)
- starts
- started
- was starting
Explanation: This question tests the distinction between future perfect and other future constructions. The phrase 'By the time she arrives' establishes a future point when another action will have been completed. Future perfect 'will have started' correctly expresses an action that will be completed before her arrival. The other options don't capture this temporal relationship: 'starts' is present tense, 'started' is past tense, and 'was starting' is past continuous. Use future perfect (will have + past participle) for actions that will be completed before a specific future event occurs.