Which act regulates employers with 15 or more employees who work for 20 or more calendar weeks in a given year?

The Americans with Disabilities Act (ADA) is the correct choice, as it specifically applies to employers with 15 or more employees, and it protects individuals with disabilities from discrimination in the workplace. The ADA aims to ensure that individuals who are qualified can participate fully in employment opportunities and have equal access to the benefits of their employment environment.

Under the ADA, covered employers are obligated to provide reasonable accommodations for employees with disabilities, unless doing so would impose an undue hardship on the operation of the business. This makes the act crucial for fostering an inclusive work environment for individuals with disabilities.

In contrast, the Family and Medical Leave Act (FMLA) pertains to employers with 50 or more employees, which does not align with the threshold mentioned in the question. The Age Discrimination in Employment Act (ADEA) focuses on protecting employees aged 40 and older from discrimination, but again, its implications differ from the context asked. The Equal Employment Opportunity Commission (EEOC) is a federal agency that enforces laws against workplace discrimination, but it does not set regulations regarding the number of employees as specified in the question.