Final answer:
The best rationale for using an incremental query instead of a standard query and scheduler is to query recipients on a daily basis.
Step-by-step explanation:
The best rationale for using an incremental query instead of a standard query and scheduler in a workflow when the request is to only send to signups within the past 30 days is option D, to query recipients on a daily basis, which is an option not available in a scheduler activity.
An incremental query allows you to run the query every day to select recipients who signed up in the past 30 days. This ensures that you are sending the email to the most up-to-date and relevant recipients. On the other hand, a standard query and scheduler activity will only allow you to schedule the query to run at specific intervals, such as weekly or monthly.
By using an incremental query, you can automate the process of identifying the recipients who signed up within the last 30 days and send them targeted emails on a daily basis. This approach saves time and effort compared to manually running a query and scheduler activity separately.