In fitness industry slang, 'training under the table' refers to training clients directly within a gym setting.

• A. Training clients via online fitness coaching
• B. Joining a gym to offer personal training directly to other members
• C. Establishing a book of business
• D. Working as an independent contractor

Answer: (B)

Training in this sense means delivering personal training services on-site, inside a gym, directly to its members. The best choice describes joining a gym and offering training to other members within that facility, which captures the on-site, gym-based service delivery the slang implies. Online coaching isn’t location-based (it happens remotely), establishing a book of business is about building clients in general rather than where you train them, and the independent contractor option focuses on your working relationship rather than specifically where the training occurs.