During the test analysis and design stage, test management tools and requirements management tools are most useful. Test management tools help in organizing and managing the testing activities, including planning, tracking, and reporting test progress. Requirements management tools assist in ensuring that the test cases are aligned with the requirements, thereby improving traceability and coverage. These tools support the efficient design and management of tests. Reference: ISTQB CTFL Syllabus V4.0, Section 5.1.2.

Functional and structural tests are types of testing techniques that can be applied at various levels of testing.
According to the ISTQB CTFL syllabus, functional and structural tests are not restricted to any specific test level but are applicable across all levels of testing. This includes component, integration, system, and acceptance testing. The use of both types of tests helps ensure comprehensive testing coverage, addressing both the functional requirements and the internal structure of the software product.

Topic 9, Scenario 6, V2 "Independent Test Team"
The project has been running for a few months and the team seems not to be progressing in their test approach. The team also lacks drive and enthusiasm and is sometimes seen to be performing their tasks too slowly. You have been asked to recruit an extra person into the team.

Debugging is the process that involves locating the cause of a failure and fixing the defect. Therefore, activities b) "Locating the cause of failure" and c) "Fixing the defect" are debugging activities. Identifying a failure and checking that the fix has resolved the failure are parts of testing, not debugging.

According to the ISTQB Glossary, regression testing is performed to ensure that changes or modifications in the software have not introduced new defects. The primary purpose of regression testing is to verify that the existing functionality of the software remains unaffected by recent changes, enhancements, or bug fixes.
The syllabus states that regression testing helps in confirming that the recent modifications do not negatively impact the previously working functionalities of the software.