* Why@TestSetup?
* The@TestSetupannotation 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: UsingseeAllData=trueis discouraged because it relies on org data, violating test isolation principles.
* D: While creating data inTest.startTest()works, it is less efficient than@TestSetupfor shared data.
References:Test Setup Methods:https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_testing_testsetup.htm