A client has requested that a business practitioner build a workflow to send an email every day at 5:00 pm to everyone who made a purchase in the previous 24 hours. Which workflow activities are necessary to meet this requirement?

The requirement is to send an email every day at a specific time to individuals who have made a purchase in the last 24 hours. To achieve this, an Incremental Query activity is suitable because it allows the workflow to query the database for records that have changed (in this case, made a purchase) since the last execution. This activity should be scheduled to run daily. The Delivery activity is then used to send the email to the population identified by the Incremental Query. There's no need for a Cell activity as there's no mention of segmenting the population further, and no Intersection activity is required as there's no secondary condition to satisfy.
Reference: This is based on the functionality of Incremental Query activities within Adobe Campaign Classic, which are designed to capture data changes over a period of time for targeted communications.