What is the likely cause for a decrease in the number of household accounts after using NPSP Contact Merge?

The likely cause for a decrease in the number of household accounts after using NPSP Contact Merge relates to the automatic deletion of any empty Household Accounts that do not have Contacts or Opportunities. During the merge process, the system consolidates information and ensures that only active and relevant accounts remain in the database. If a household account is left with no associated contacts or opportunities as a result of the merging process, the system identifies these empty accounts as redundant and removes them to maintain data integrity and efficiency. This helps organizations keep their databases clean and focused on accounts that are meaningful and active within the NPSP framework.

The other options do not accurately reflect the functionality of the merge process. For instance, merging does not create new Household Accounts nor convert existing ones into custom object records, nor does it simply combine the accounts without consideration of their contents. The focus of the NPSP's merge functionality is to streamline and maintain the quality of the data by removing unneeded duplicate records.