Final answer:
The illegal interview question for the purpose of discrimination is asking about the applicant's disabilities in relation to job performance, which is against the EEOC guidelines.
Step-by-step explanation:
The question regarding which interview question is illegal for the purpose of discrimination refers to the practices governed by the U.S. Equal Employment Opportunity Commission (EEOC) and related laws. Among the options provided, the question 'D. Do you have any disabilities that may affect your ability to perform the job?' is the one that is illegal to ask because it directly addresses a potential disability and may lead to discrimination against the applicant. Instead, employers should focus on whether an applicant can perform essential job functions with or without reasonable accommodation, which does not involve disclosing whether or not they have a disability.