Which of the Following Statements Is TRUE as a General

Which of the following statements is TRUE as a general rule?

A) Property passes under an unconditional contract for the sale of specific goods in a deliverable state only once the buyer pays the price.
B) Property passes under a contract that requires the seller to modify the goods in order to put them into a deliverable state only when the goods are delivered to the buyer.
C) Property passes under a contract that requires the seller to do something to ascertain the price of the goods as soon as the price is determined.
D) Property passes under a contract "on sale or return" only if the buyer pays the price.
E) Property passes under a contract that requires the seller to test the goods as soon as the seller does so and notifies the buyer.