Under Common Law, Which of the Following Is an Example

Under common law, which of the following is an example of a valid contract following the "mirror image" rule?

A) Tibb offers to sell his bike to Rony for $10,000 and gives a written promise to keep the offer open for 10 days. Rony responds on the 11th day saying that he will pay $15,000 for the bike.
B) Tibb offers to sell his bike to Rony for $10,000 and gives a written promise to keep the offer open for 10 days. Rony responds on the second day saying that he will pay $5,000 for the bike.
C) Tibb offers to sell his bike to Rony for $10,000 and gives a written promise to keep the offer open for 10 days. Rony responds on the second day and accepts the offer along with the condition that Tibb gets the bike serviced.
D) Tibb offers to sell his bike to Rony for $10,000 and gives a written promise to keep the offer open for 10 days. Rony responds on the second day accepts the offer with the proviso that Tibb fill the fuel tank.
E) Tibb offers to sell his bike to Rony for $10,000 and gives a written promise to keep the offer open for 10 days. Rony responds on the second day saying that he is ready to accept the offer and that he would also like a helmet.