The correct answer is A. Account Object .

Roll-up summary fields are created on the parent object , because the summary value is displayed on the parent record. Here, the KPI values need to appear for each Account , and they summarize related Opportunity records. Therefore, the app builder should go to the Account object in Object Manager and create roll-up summary fields there.

For this requirement, the app builder would create separate roll-up summary fields on Account, such as:

Count of open Opportunities

Count of won Opportunities

Salesforce documentation describes roll-up summary fields as fields that calculate values from related records, such as records in a related list.

C. Opportunity Object is incorrect because Opportunity is the child/related record being counted.

D. Lightning App Builder is incorrect because Lightning App Builder controls page layout/components, not the creation of roll-up fields.

B. Lightning Object Creator is used to create objects from spreadsheets, not build rollups.

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