The correct approach in this scenario is option D: Revert to Service 1, take a snapshot, and apply the Service 1.5 patch.
Let’s break down the reasoning behind this choice:
Revert to Service 1: Since the administrator realizes that the Service 1.5 patch should have been applied before the Service 2 patch, it’s best to revert to the state before the Service 2 patch was applied. This means rolling back to Service 1.
Take a snapshot: Before making any changes, take a snapshot of the current state. This snapshot will serve as a backup in case anything goes wrong during the patching process.
Apply the Service 1.5 patch: After reverting to Service 1, apply the Service 1.5 patch. This ensures that the correct patch is now in place.