The two correct statements about using the @testSetup annotation in an Apex test class are:

A. A method defined with the @testSetup annotation executes once for each test method in the test class and counts towards system limits.

D. Test data is inserted once for all test methods in a class.

**Explanation:**

- **Statement A** is true because the method defined with @testSetup runs once before each test method in the test class, meaning it sets up test data that each test method can use without having to create it again. This can help keep within system limits for DML operations and queries.

- **Statement D** is true because the test data inserted by the @testSetup method is created once and shared among all test methods in the class. This helps in avoiding redundancy and makes the tests more efficient.

**Incorrect Statements:**

- **Statement B** is incorrect because the @testSetup annotation is supported even when the GisTest(SeeAllData=True) annotation is used, although it is generally not recommended to use SeeAllData=True.

- **Statement C** is incorrect because records created in the test setup method can be updated in individual test methods. The @testSetup method just creates the initial data, and test methods can modify it as needed.

For more detailed information, you can refer to the [official Salesforce documentation](https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_testing_testsetup_annotation.htm)....

CD correct

B and D correct ones.