You are migrating your on-premises PostgreSQL database to Spanner. You need to identify a solution for handling existing integer-based table primary keys. You want minimal changes to the applications while also following Google-recommended practices. What should you do?

A. Use application generated sequential integer values as primary keys. B. Update default primary key values to max(primary_key) + 1. C. Use a UUID function that generates UUID Version 4 values as primary keys. D. Generate values by using BIT_REVERSED_POSITIVE sequences.