I have this question to answer any clues pleeeaaaasssse?

2. Xavier writes to Yvonne on 1st November offering to sell 500 bottles of 鈥楤eaujolais Villages鈥?at 拢2 per bottle and stating that the offer 鈥榳ill remain open only until 5pm on 5th November鈥? Yvonne receives the letter at 9am on 5th November and immediately tries to telephone Xavier. Xavier, however, is out and therefore Yvonne leaves a message on his answering machine asking if he would agree to 拢1.85 per bottle.
Later that morning, Yvonne changes her mind and sends Xavier a fax stating: 鈥楧isregard earlier phone call. I accept your offer at 拢2 per bottle鈥? Xavier returns to his off-licence at 1pm and, after hearing Yvonne鈥檚 telephone message, he decides to sell the wine to Zachary who happens to be in the shop at the time. At 2pm Yvonne鈥檚 fax is passed to Xavier by his secretary.
Discuss the legal position of Xavier, Yvonne and Zachary

I'm not going to answer these questions directly. I'll just frame them so you can actually do the work.

X - presented Y with an offer with conditions (open until 5 PM on November 5.)

Y - called during the open period and asked if he would agree to a change in a material term (price). ISSUE: Is requesting a change in a material term considered a rejection entitling the offeror to offer the goods to another? Is a question of a material term by an offeror actually a counter offer?
Y - sent a fax accepted X's offer. ISSUE: Is sending a fax a valid acceptance? What constitutes a valid acceptance (mailbox rule)?
ISSUE: Was X's offer still valid until 5:00?

Z - ISSUE: What are the rights of a third party beneficiary for value. (I assume he had no knowledge of X's offer to Y)

There are probably more issues that you can flesh out but I think this is the basic framework to begin. Have fun!

An offer to sell does not imply a contract. He can sell them to who he likes at whatever price he likes. There is nothing to discuss.

Guy above was absolutely right. There is no contract or obligation to sell the wine to Yvonne. Even if Xavier had not sold to Zachery, because there is no contract, he is not compelled to sell to Yvonne.