Commissions can be received by

While an introducing referrer may help connect clients with service providers, they usually do not have the authority to finalize contracts or engage in business transactions directly. Their role is primarily to generate leads rather than to act in a capacity that would earn them commissions, making this option incorrect.

A service representative typically provides support and information about products or services but may not engage in direct sales or transactions that would qualify for commission-based earnings. Their role is usually more focused on customer service rather than the authority to negotiate deals, which limits their commission-earning potential.

An appointment scheduler is responsible for organizing meetings and appointments but lacks the authority to negotiate or finalize deals. Their position does not involve direct involvement in transactions that would lead to earning commissions, making them ineligible in this context.