Explanation:

Microsoft Entra ID (Azure AD) supports soft-delete for application objects for 30 days after deletion. The SC-
300 materials explain that administrators can recover deleted applications within 30 days; objects deleted beyond that window become non-recoverable. The guide also distinguishes between the application (app registration) and the service principal (enterprise application): the app registration contains credentials (client secrets/certificates) and app role definitions, while the tenant's service principal contains tenant- specific settings such as assignments and self-service configuration. The study content states that recovery operations restore the deleted application object and its schema (including defined app roles and credentials) if performed within the retention window, whereas tenant-scoped assignments and end-user self-service settings are not guaranteed to be recovered because they are specific to the service principal in the tenant.
Applying this: the apps were deleted April 5 and restoration is attempted April 16, which is inside the 30-day window. However, the exam scenario emphasizes the timing of tenant-side updates in March; App1's updates are older than 30 days by April 16, so it falls outside the reliable recovery period for those settings, while App2-App4 remain within it. For App4, the restorability applies to the application object contents- app roles and the client secret-not the tenant-specific Users and groups assignments or Self-service configuration. Hence: Apps = App2, App3, and App4 only; App4 settings = App roles and Client secret only.