A company is migrating a self-managed on-premises database and wants to move it onto a managed AWS database (Amazon RDS) without changing the core functionality, in order to reduce operational burden. Which migration strategy is this?
A question asking which migration strategy optimizes by making part of the workload managed.
Replatform
This is correct. Replatform (lift, tinker, and shift) is a strategy that keeps the core of the application unchanged while replacing part of it with managed services to optimize it. Moving a self-managed database onto managed RDS to reduce operational burden is a typical example.
Rehost
Rehost is a strategy that moves an application almost unchanged, as is.
This question includes replacing with a managed service to optimize, which differs from a plain unchanged move, so this is incorrect.
Retire
Retire is a strategy that decommissions applications that are no longer needed.
In this question the DB is migrated and kept in use, which differs from decommissioning, so this is incorrect.
Retain
Retain refers to the decision to keep something on-premises for now and not migrate it.
In this question it is moved onto AWS, which is the opposite of keeping it, so this is incorrect.
Replatform = keep the core while making part managed to optimize (for example, self-managed DB → RDS). Fully unchanged is Rehost, and a full rewrite is Refactor; distinguish them by degree.