Answer:
C) Harry (broker Harry to be more exact)
Step-by-step explanation:
When a seller signs an agency agreement, he/she signs a contract with the broker, not with the broker's employees.
Depending on the type of agreement that the seller signed with broker Harry, the seller will have to pay one or two sales commissions.
If the seller singed an open listing agreement then he/she will only pay the selling commission to broker Sam (Mary works for him), but if the agreement was an Exclusive Agency Listing or an Exclusive Right-to-Sell Listing, then the seller will have to pay a commission to broker Harry also.