Answer: Assign the Cloud Spanner Database Admin role.

To assign the required privileges to all members of the application development team on a specific database, we need to consider the permissions each role provides. The Cloud Spanner Database Reader role allows reading tables, views, and DDL, but does not permit writing rows to tables or adding columns and indexes. The Cloud Spanner Backup Writer role is not relevant here as it pertains to backup operations. The Cloud Spanner Database Admin role provides all the required permissions including reading tables, views, and DDL, writing rows to tables, and adding columns and indexes, but it also allows dropping the database, which is not desired. The Cloud Spanner Database User role allows reading and writing data but does not permit adding columns and indexes. The Cloud Spanner Admin role is too broad as it provides full control over all Cloud Spanner resources, not just the specific database. Therefore, none of the options perfectly match the requirements, but the closest is the Cloud Spanner Database Admin role (B), despite it including the ability to drop the database, which is not desired. However, since the question asks for the best available option, B is the most suitable.

Author: LeetQuiz Editorial Team