Fred Contracts to Sell a Certain Tract of Land to Mary

Fred contracts to sell a certain tract of land to Mary for $20,000, but the contract is silent as to the time of delivery of the deed and payment of the price. In this case:

A) the payment of the $20,000 and the delivery of the deed are independent of each other.
B) the delivery of the deed is a condition subsequent to the payment of the $20,000.
C) the payment of the $20,000 and the delivery of the deed are mutually dependent and, in the absence of an agreement to the contrary, are concurrent conditions.
D) the payment of the $20,000 is a condition precedent to the delivery of the deed.