Which of the following is a LEGAL question an interviewer can ask a job candidate?

The question "Are you physically able to perform this job?" is legally acceptable for an interviewer to ask because it relates directly to the candidate's ability to fulfill the essential functions of the job. Employers have the right to assess whether applicants possess the necessary physical capabilities required to perform tasks associated with the role they are hiring for. This question does not delve into personal characteristics such as age or marital status, nor does it inquire about disabilities in a manner that could discriminate against the candidate, making it compliant with employment laws.

The other options, while potentially relevant in discussions about qualifications, touch on personal information that could lead to discrimination based on age, marital status, or disability, which are protected categories under employment laws. Hence, such inquiries are generally prohibited in interviews to ensure fairness and compliance with regulations against discrimination in the hiring process.