Answer: b. "We can prevent delaying the third phase of our campaign if we send out the reports on time."
Explanation:
For Alyssa to write a persuasive direct request to Elizabeth asking for the progress report, she can write "We can prevent delaying the third phase of our campaign if we send out the reports on time"
The emphasis here is about being proactive and not delaying the work on ground so that the task will be completed on time. When compared to other options, it'll lead to non-delay of the task and the task will be sent on time rather than sending it when Elizabeth feels like sending it.