A roll-up summary field is a field that calculates values from related records. A roll-up summary field can be used to display the number of opportunities that are closed won with a close date within the last year on the account detail page by using a filter criteria on the field.

To show Component as a related list on Product, a lookup relationship on Component to Product should be created. A lookup relationship creates a loose association between two objects and allows users to relate records from one object to another. A lookup relationship also allows users to add the related list of the child object to the parent object's page layout.

Moving the reports from the Unfiled Public Reports folder and adding them to a new change set is what the app builder should do to deploy the reports to production. According to the Salesforce documentation, "Reports in the Unfiled Public Reports folder aren't available for deployment." Moving the reports to the Untried Public Reports folder, recreating the reports in production, and adding the reports to an unmanaged package are not necessary or recommended actions.

The solution that an app builder should use for this request is a lookup field. A lookup field is a type of relationship field that links two objects together and allows users to select a record from another object. The app builder can create a lookup field on the account object that references the user object and allows users to assign a customer service manager (CSM) to the account. Option A is incorrect because a multi-select picklist field is not suitable for this request, as multi-select picklist fields allow users to select multiple values from a predefined list, not from another object. Option B is incorrect because a picklist field is not suitable for this request, as picklist fields allow users to select one value from a predefined list, not from another object. Option D is incorrect because a text field is not suitable for this request, as text fields allow users to enter any alphanumeric characters, not from another object.

The app builder should create a new roll-up summary field called First Order Date, using Type MIN on the Opportunity Close Date with a filter where IsWon = TRUE. A roll-up summary field is a type of field that calculates values from related records and displays them on the parent record. In this case, the app builder can create a roll-up summary field on the Account object that calculates the minimum (earliest) value of the Opportunity Close Date field from the related opportunities where IsWon = TRUE. This will show when customers made their first purchase. Option B, C, and D are not correct ways to use a roll-up summary field to meet the requirement.