To performincremental backupsusing thewebgisdr tool,point-in-time recoverymust be enabled on the relational data store. This creates transaction logs needed for differential backups and aligns with best practices for enterprise-level backup strategies.
From Esri documentation:
"Incremental backups can only be used with a relational data store when point-in-time recovery is enabled.
This enables transaction log capture needed for delta backups."
* OptionAis unrelated to backup functionality.
* OptionCis not required unless performance tuning is needed.
Reference:ArcGIS Enterprise -Enabling Point-in-Time Recovery in ArcGIS Data Store for Incremental Backups

ArcGIS GeoAnalytics Server is designed to perform distributed analysis on large volumes of spatial and temporal data. It is particularly suited for workflows that involve analyzing patterns over time and space, such as identifying interstates with the most incidents over decades and correlating vehicle behavior (like speeding and braking) with accident locations.
GeoAnalytics Server provides tools for aggregating data, detecting incidents, and reconstructing tracks, which are essential for understanding complex transportation datasets. Its distributed computing framework allows for efficient processing of big data, making it the appropriate choice for the described workflow.
GeoEvent Server (Option B) is primarily used for real-time data processing and event detection, which is not the focus of this analysis. Notebook Server (Option C) supports interactive data science and analysis workflows using Jupyter notebooks but does not provide the same level of performance and scalability for big data analysis as GeoAnalytics Server.
Reference Source:ArcGIS Enterprise documentation on GeoAnalytics Server capabilities and use cases.

Registering the database as a data store item in the ArcGIS Enterprise portal allows administrators to control who can publish services referencing the data. By sharing the data store item with specific groups or individuals, administrators can restrict publishing capabilities to authorized users. At the same time, all users can be granted appropriate permissions to access and edit the data directly in the user-managed database, independent of the publishing privileges.
Registering the database as an ArcGIS-managed data store in Server Manager does not provide the same level of control over publishing permissions. Registering it as a relational data store in ArcGIS Data Store is intended for managed data storage and does not apply to user-managed databases.
Reference Source:ArcGIS Enterprise documentation on registering user-managed data stores and controlling access.

ArcGIS Enterprise Sites is a capability within ArcGIS Enterprise that enables organizations to create tailored web pages for sharing data and content. These sites are designed to be user-friendly for non-GIS users, allowing them to interact with, download, and create applications from the organization's data. Since the organization does not have access to ArcGIS Online, ArcGIS Enterprise Sites provides the necessary functionality within their existing deployment.
ArcGIS Hub (Option A) is a separate product that requires ArcGIS Online. ArcGIS Experience Builder (Option C) is a tool for creating web applications but does not provide the comprehensive site-building capabilities needed for this scenario.
Reference Source:ArcGIS Enterprise documentation on Sites

When expanding an ArcGIS Server site from one to three machines, the number of ArcSOC processes (service instances) will increase proportionally. For dedicated instances, each service's minimum and maximum instances are configured per machine, so tripling the number of machines will triple the number of dedicated ArcSOCs. For shared instances, the shared instance pool runs on each machine, and the number of shared instances is configured per machine. Therefore, the total number of ArcSOCs (both dedicated and shared) will be approximately three times greater after the expansion