Final answer:
The Age Discrimination in Employment Act of 1967 (ADEA) was violated when the 67-year-old applicant's job application was dismissed based on age, which is enforced by the EEOC.
Step-by-step explanation:
The federal regulatory requirement that was violated when the supervisor reviewed the applications and accessed a publicly available social media site specifically to determine the birth year of the applicants, and then eliminated the 67-year-old applicant from consideration is the Age Discrimination in Employment Act of 1967 (ADEA). This act makes it unlawful for any employer to fail or refuse to hire, or to discriminate against any individual with respect to compensation, terms, conditions, or privileges of employment, because of the individual's age. The U.S. Equal Employment Opportunity Commission (EEOC) is responsible for enforcing federal laws that make it illegal to discriminate against a job applicant or an employee based on age (40 or older).