A campaign business practitioner is monitoring a delivery during its analysis. The campaign business practitioner notes that the audit has indicated two items with a warning. What happen with the delivery because of the warning?

A Business Practitioner has a delivery with two links sent to 100 recipients:
80 messages reached the box
40 Recipients opened the delivery
20 Recipients clicked on at least one link
What was the reactivity?

The sent count is less than the upstream population. What are two reasons for this result? (Choose two.)

Sub-population A of 100 records and B of 200 records are combined in a campaign workflow with a Union activity. The resulting population C contains 200 records.
What should the Practitioner conclude?

A query returns 0 records for a specific date. What is the most efficient method to determine what dates exist in the table?