Universal Containers uses a custom picklist called `Account_Region ` or the Account object.

The correct answer is B. Cross-object formula.

Opportunity has a standard relationship to Account, so an app builder can create a formula field on Opportunity that references the parent Account field. Salesforce defines a cross-object formula as a formula that spans related objects and references fields on those related objects.

Because Account_Region__c is a picklist on Account, the Opportunity formula would commonly be a text formula like:

TEXT(Account.Account_Region__c)

Field history tracking only tracks changes, a lookup field would create a relationship rather than display the Account field value, and field-level security controls visibility but does not copy or display the parent field on Opportunity.

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