Answer:
B. must return all of the deposit, but may then sue the seller for his commission
Explanation:
A broker has the obligation to return all the money back to the seller if the seller decides to cancel the order. This being said if the seller decides to cancel the order the broker has the choice of suing the seller for the broker's commission. This is because regardless of whether the seller decided to cancel or not the order was placed which means that the broker did his job and can ask for the commission. Therefore the answer is B.
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