Alpha and Beta testing are forms of

Alpha testing and Beta testing are performed to check whether the software is acceptable to users.

Alpha testing is usually done at the developer side by internal users or testers.

Beta testing is done by real users in the real environment before final release.

Both are used to validate the software from the user's point of view.

Therefore, Alpha and Beta testing are forms of Acceptance Testing.

Now check the options:

White-Box Testing checks internal code structure.

Black-Box Testing checks functionality without seeing internal code.

System Testing checks the complete system.

Acceptance Testing checks whether the software is acceptable for final use.