Which of the Following Statements Is TRUE as a General

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

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