The correct selection is A, C. High code coverage alone does not guarantee useful tests. Test scripts should drive meaningful Apex scenarios and detailed acceptance criteria should define observable behavior, ensuring automated tests validate the actual requirement rather than merely execute additional lines of code. From a testing perspective, the goal is deterministic evidence that the solution behaves correctly under the conditions that matter. Tests should isolate external dependencies, use controlled data, exercise positive and negative paths, and reproduce realistic volume or user behavior where required without making production the first place defects are discovered. The rejected choices either test the wrong layer, introduce live-system dependencies, or detect problems too late to provide the deterministic early feedback expected from a mature test strategy. For this scenario, the decisive point is therefore the platform behavior represented by the selected options (A. The test script should be used to define the test classes.; C. The acceptance criteria should have more details.). Applying that rule consistently keeps the implementation aligned with Salesforce-supported lifecycle practices and makes the resulting change easier to review, validate, and operate across environments.

Study Guide reference: Testing — Apex testing; test-data isolation; mocks; regression testing; performance/load testing; sandbox test strategy.