* Why @TestSetup?
* The @TestSetup annotation creates a baseline set of test data once per test class.
* Test methods reuse this data, avoiding the need to recreate it repeatedly, which improves efficiency.
* Why Not Other Options?
* A: HttpCalloutMock is used for mocking callouts, not for creating test data.
* C: Using seeAllData=true is discouraged because it relies on org data, violating test isolation principles.
* D: While creating data in Test.startTest() works, it is less efficient than @TestSetup for shared data.
* Test Setup Methods: https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode
/apex_testing_testsetup.htm
References: