Prioritize Record allows users to rank possible values for the field specified in the "for field [dropdown]" when a merge rule is executed to populate the field specified by the [dropdown] field within the master record.
Using the following block, the record with the Status equal to "Declined" has highest priority to fill the Status field within the Master Record, otherwise the record with Status equal to "Working" will be second and a record with Status equal to "New" is third priority. Finally if a record has a Status that doesn't match "New, Working or Declined", the record with the highest/newest Created Date will be the record that fills in the Status field within the Master Record as a catch-all.
Note: "and prioritize" block overrides previous selection, in the example above, if any of the records in a group has a status "Declined", it will be the surviving value, then "Working" and lastly "New".