TriNet's Knowledge Practice Test

A Professional Employer Organization (PEO) provides co-employment and handles HR tasks like payroll, benefits, and compliance for client companies. Among the names listed, ADP, Paychex, and Insperity are known PEOs that offer these HR outsourcing services and are publicly traded. Aon, while publicly traded, operates mainly as a professional services firm focused on risk management, insurance brokerage, and advisory services, not on co-employment HR outsourcing. So Aon is not a PEO, which is why it’s the correct choice.