In Salesforce, there are different types of sharing: Managed Sharing (Role Hierarchy, Sharing Rules) and Manual Sharing. A critical behavior of the platform is that when a user is deactivated, all their Manual Shares (records shared with them by other users using the "Share" button) are automatically and permanently deleted from the system. Even if the user record is reactivated later, those manual shares do not return. Because the organization uses a "Private" model and does not use criteria-based sharing rules, the user's previous access likely relied on manual sharing or their previous position in the hierarchy. While activating the record and adding them back to teams provides new access, the historical "one-off" shares are gone. Options A and B are unlikely to be the cause of a total loss of visibility. Option D is incorrect because permission sets control what a user can do, not which specific records they can see in a private sharing model.

In Salesforce, a flow must be Active for it to execute in a production environment. When an administrator builds or updates a flow, it is saved as a new version. Even if the logic is perfect and passes all debug tests, the flow will not run for end-users unless the administrator explicitly clicks the "Activate" button. If a flow is intended to create records but nothing is happening, the first troubleshooting step is always to verify the status in the Flow Builder or the Flows list in Setup. A flow version that is simply "Saved" but not "Active" will remain dormant. Option D is unlikely because the Flow Builder usually prevents saving a record-triggered flow without a trigger defined. Option C ("Read Only") is not a state that would prevent a flow from running. Option B ("Flow URL") only applies to specific types of screen flows launched via custom links, whereas the question implies a general failure of the automation to execute.

A Roll-up Summary Field is a powerful feature that calculates values from related records and displays them on a master record. However, this functionality is natively available only on the "Master" side of a Master-Detail relationship. For standard objects, Salesforce provides a built-in Master-Detail-like relationship between Accounts and Opportunities . Specifically, the Account object acts as the master, and the Opportunity object acts as the detail. This relationship allows a Platform Administrator to create roll-up summary fields on the Account to calculate the sum of "Total Opportunity Amount," the "Minimum Close Date," or a "Count" of all related opportunities . Other standard objects like Contacts (Option B) and Cases (Option C) have a lookup relationship to Accounts rather than a master-detail relationship, and therefore do not support native roll-up summaries20. Campaigns (Option D) also do not share this specific relationship with Accounts21. If an administrator needs to roll up data from these other objects, they would typically need to use a custom solution like Flow Builder or a third-party app, whereas Opportunities are supported natively out of the box .

When an administrator needs to extract a specific subset of records (e.g., Opportunities filtered by stage and date) with specific fields, the Data Loader is the most appropriate tool . Data Loader is a client application that allows for bulk operations, including "Export" and "Export All"43. It allows the administrator to write a SOQL (Salesforce Object Query Language) query or use the built-in query builder to apply filters, such as StageName = 'Closed Won' and CloseDate = LAST_90_DAYS44. The Data Import Wizard (Option B) is primarily used for importing data and has very limited export capabilities, usually confined to simple CSV samples45454545. The Data Export Service (Option D), also known as "Weekly Export," is designed for full backup purposes; it exports the entire database into zip files and does not allow for specific filtering of records or fields for a quick ad-hoc report . Data Cloud (Option C) is a large-scale data platform and is overkill for a simple file export task47. Thus, for targeted, field-specific exports of 90 days of data, Data Loader is the standard choice .

When an object's Organization-Wide Default (OWD) is set to Private, the "Record Sharing" engine must be used to grant additional access.
Sharing Rules: These allow the administrator to grant lateral access to records based on criteria or ownership (e.g., share all "Large Deals" with the "Strategic Sales" group).
Role Hierarchy: This standard feature automatically grants vertical access, ensuring that managers and users higher in the hierarchy can see and edit records owned by their subordinates.
Profiles (Option D) control what actions a user can perform (Create, Read, Edit) but do not grant access to specific records that the user does not own in a Private model. A Sharing Set (Option B) is a specific feature used for Experience Cloud (Community) users to grant them access to records related to their account and is not used for standard internal sales users.