Enabling granular locking allows concurrent sharing rule calculations and group membership updates to run without locking each other. This can help resolve the group membership locking issues that UC is experiencing.

Identifying a location to store archived data and using scheduled batch jobs to migrate and purge the aged data on a nightly basis can be a way to meet the requirements for an archive solution.
The article provides a use case of how to use Heroku Connect, Postgres, and Salesforce Connect to archive old data, free up space in the org, and still retain the option to unarchive the data if needed. The article also explains how this solution can improve Salesforce performance and meet data retention policies.

Creating a Dashboard using Analytics Cloud that will allow the user to create ad-hoc lenses and drill down is a recommended solution for building data exploration dashboards in Salesforce.
Analytics Cloud is a powerful data analysis tool that enables users to explore data using interactive dashboards, charts, graphs, and tables on any device. Users can also create lenses, which are ad-hoc data queries that can be saved and reused, and drill down into data details using filters and facets. Creating a Dashboard in an external reporting tool, exporting data to the tool, and adding link to the dashboard in Salesforce will not provide a seamless user experience and may require additional data integration and security considerations. Creating a Dashboard in an external reporting tool, exporting data to the tool, and embedding the dashboard in Salesforce using the Canval toolkit will not provide a native Salesforce solution and may require additional data integration and security considerations. Creating a standard Salesforce Dashboard and connecting it to reports with the appropriate filters will not allow the user to create ad-hoc lenses and drill down into data details on their mobile device.

According to the Using Mashups article on Salesforce Developers, one of the techniques for deploying large data volumes is to use mashups to display historical records in Salesforce. The article states that "Mashups are a way to display data from an external system within a Salesforce page without copying or synchronizing the data. Mashups use a combination of Visualforce, Apex callouts, and JavaScript code that runs in the browser. Mashups are useful when you want to display large amounts of read-only data that is stored outside of Salesforce." Therefore, a data architect should recommend this solution to meet the business requirement of UC.

The correct answer is B. To make changes efficiently, a data architect should enable Defer Sharing Calculation prior to making sharing rule changes. This will allow the administrator to make multiple changes to sharing rules without recalculating them after each change, which can take a long time and cause failures. The sharing rules can be recalculated later when there are fewer users online or during off-peak hours.