B:@testSetupinserts data once and shares it across all test methods in the class, saving system resources.
D:@isTest(SeeAllData=true)is incompatible with@testSetupdue to their differing purposes for managing test data.
Reference:@testSetup Annotation
Incorrect Options:
A:Records can be updated in individual test methods.
C:@testSetupdoes not execute repeatedly; it runs once per class.