Which of the Following Is True of Real Estate Commissions

Which of the following is true of real estate commissions?

A) If the seller has not given the broker a specific closing date,the broker can assume a reasonable closing date and can also claim a commission for an incomplete sale.
B) If the seller has not given the broker specific terms on price,the broker can sell the property on his own terms and claim for the commission.
C) If the seller has not given the broker a specific closing date,the law assumes the contract to end 30 days after the creation of the contract,but the broker will not be entitled for a commission.
D) If the seller has not given the broker specific terms of price or closing date then the commission is not earned until the contract of purchase has been made.